Ugh, I just lost all of what I typed due to Win7 and Synaptics touchpad's useless palmcheck. So frustrating!
At any rate, I think you'll want to do some deep digging into every MODX tutorial you can find. Use google to search for MODX tutorials, MODX templates, MODX chunks, etc.
Some (many) of them will be for Evolution. There's not a whole lot of difference in the overall concepts between Evolution and Revolution so for the most part, you can use those tutorials as long as you remember to use the Revolution tags instead of Evolution tags.
[*content] - Evolution tag
[[*content]] - Revolution tag
Insofar as your site - it sounds like you've pasted the code into the content area of the MODX pages. What you want to do is divide that code up into areas that remain constant such as the <head> and <header> (the top of your html file, down through the constant header and menu), and the footer area. These portions of your site don't change often, but when they do you'll want to make one edit and have it dynamically display across your site on all pages. If you have static pages, to make one tiny change in the head you'll have to change every page manually. By putting these portions in either the template or a chunk that the template calls up with MODX tags you can make that change once and then forget about it.
You can either place these things into chunks or put them directly into the template. I learned the chunk method, so that's what I do. My template looks like this:
[[$site_header? &showParent=`true`]]
<div class=grids><h1>[[*pagetitle]]</h1></div>
[[*content]]
[[$site_footer]]
The first tag calls up my header chunk which is a chunk I made that holds everything from the top of the pags down to the menu. Then you see a <div> which holds my pagetitle (pulled from MODX) which displays right under my menu. Next is the site content which comes from that area in the pages where I think you pasted your code. After that, is my footer chunk. That's it for my template. I could have any number of page templates with different looks calling different chunks.
You can however, put your html into the template itself and not use a site_header chunk but for me, that's how I learned it and I'm likely going to stick with it.
You will get the same result from using chunks as you will from using the template itself to house the un-changing html for your pages. Change a chunk, it changes across the site wherever you call that chunk. Change the template, it changes on every page that you use the template on. Easy!
In it's most basic concept... that is what MODX does to make your life easier. But it does much much more and you'll want to use things like Wayfinder to call up your menu so that if you create a new page, it automatically adds it to the menu instead of you having to go into the menu and manually code it in. For other constants (such as sidebars or other chunks of information on your site that you will want to insert and remove on different pages as you desire) you'll want to put those things into chunks and TV's which you'll simply call up with MODX tags wherever you want them placed. The chunks hold the actual code, and the TV's allow you to change the information that the chunk displays. It should all fall together like a puzzle that you can change the look or content of each piece or use the same puzzle piece over and over again anywhere you want without having to write any new code. Ideally... lol
A bit of warning... it does take time. I've been working with MODX, teaching myself (a 41yo mama of 3 who created her first database on her dad's IBM XT in 1986) EVERYTHING from beginning html and CSS, PHP and mySQL, JavaScript, etc for a couple of years now. I knew lots about computers in general, but next to nothing about websites. I found MODX a little over a year ago and have quite a few local MODX sites on my machine just to practice with. I've been recently introduced to WordPress because a client who chose not to hire me and let a friend set up his site has now asked me to fix it. UGH! OK, it's all kinds of awesome in so far as getting something done quickly and easily but it's also frustrating because it's not MODX and I get what I get for the most part. I know MODX can do all that WP does and a million things more, and furthermore I can make it do it my way instead of someone else's. I've decided to focus on html5 and css3 and responsive web design instead of look too far back to the past and re-invent the wheel. MODX allows me to do that. In WP... I get... whatever I get and all it really is, is just a blog that people have made work for commercial sites. I find it more frustrating to back track and re-do than to just do from scratch usually.
As far as tutorials, just search for them. Google with "MODX" in your search string and it'll all show up. A few of my favorites are:
http://codingpad.maryspad.com/tag/modx-tutorial/
(Evo and Revo are different, yet similar - just note it)
http://sottwell.com/
http://bobsguides.com/
(anything in the above three sites are pure gold - read!)
http://designfromwithin.com/
(fabulous tutorials and videos)
http://modxrules.com/
http://wiki.modxcms.com/index.php/Beginner's_Guide_to_MODx
(this is for Evolution, but it's worth reading as long as you differentiate between Evo tags and Revo tags plus some other things that don't apply to Revo - you'll see...)
And of course, the official docs at:
http://rtfm.modx.com/display/revolution20/Home
You can search youtube for MODX, and a number of videos are available on Vimeo as well. The videos really do help so watch whatever you can.
Additionally, I can't recommend more to get a copy of the MODX - The Official Guide by Bob Ray
http://modx.com/learn/modx-books/modx-the-official-guide/.
I just got my copy yesterday and went directly to the php appendix with my highlighter. That's one thing that I am ultra confused about and I have to say that after reading and highlighting for just a couple of hours, things are finally beginning to fall into place. I'm so happy to have it in my hot little hands. Now if I could figure out exactly how to set the toPlaceholder property to "files" without mucking up the rest of the properties...
)