how to make version of modx database

Hi,
I want to make different versions of modx resources and database
.. I use modx 1.0.4
thnx..

What exactly do you want to do? You can make a backup of your current MODx database and restore it on another MODx site as long as its the same version since they still haven’t released the Evolution to Revolution migration tool.

My problem is that if suppose my site( made on modx) is published and now I want to edit my snippet or a chunk..wouldn’t that alter my published site. How can I edit a snippet or a chunk in use?

Not sure I understand exactly. The only reason you would edit a snippet or chunk is if you want to alter your published site. The site will use the existing version until you click "Save".

If you’re not sure about the changes you’re making, create a new snippet/chunk instead, so you can test them on an unpublished page.

My point is that I don’t want my temporary editing to be seen on the site (just wish to preview it) and at the same time don’t want to unpublish my page.

I have a section in my Tree called "tools" where I have various resources that aren’t for actual public view (or at least not from the menu). I’ll have pages like the search landing page, custom not-found or unauthorized page, and at least one "testing" page. So I would duplicate the page in question, move the duplicate to my "tools" section, then try out my changes on the test page. If I’m really feeling paranoid, I’ll unpublish it so nobody but logged-in manager user can see it at all even if they somehow know the alias or resource ID to use in the browser address bar. When I’m happy, I can either move the test page to the main area again and move the original one to the Tools section for re-use later, or do the changes to the original.