Help needed with Free's gallery/portfolio

I’m trying to implement Free’s gallery/portfolio (see http://modxcms.com/extras/package/549 ), but I cannot get the image gallery/showcase in the upper left to appear. I read the instructions, but don’t understand how this is supposed to work. I tried:
- creating a document folder containing all of the images
- then filling in the TV’s
- changing the Ditto call to the root folder’s ID

How does this work essentially and what do I need to do to make the image gallery/showcase appear?

Okay, I guess I’ve been a bit too vague/broad.

My problem is, there are a couple of calls of which I am unsure what they are for and what structure the documents should have.

- Gallery Item template:
[!Ditto? &startID=`28` &display=`12` &sortBy=`ASC`
&tpl=`thumbGallery`!]

---> startID refers to what kind of document? Nested pages/folders with an image value in their TV’s?

- Chunk G-header
[!Wayfinder?&startId=`29`&level=`1`!]

---> I suppose this is the top level document for the website?

- Chunk G-footer
[!Wayfinder?&startId=`29`&level=`1`!]

---> I suppose this is the top level document for the website, same as above?

[!Wayfinder?&startId=`28`&level=`1`&limit=`6`!]

---> Where the pictures are?

- Chunk photoblock

[!Ditto? &startID=`28` &summarize=`6` &total=`6` &tpl=`thumbGallery` &filter=`featured,1`!]

---> Where the pictures are; and show only if featured="yes"?

Okay, I figured out how it should work. One thing got me confused though, I could not get the gallery on the homepage displaying. That is because the ’photoblock’ reference is -I think- missing in the Main Page template. So I believe it should be something like this (bold is what I added myself).

<div id="sidebar">
[*sidebar*]
{{photoblock}}
</div>

And it works now.