Some questions for getting started
Using Jamroom
Welcome to Jamroom!
The level of skill required is going to depend on what you're looking to do - if you just want to tweak a few things here and there (i.e. change colors, add a menu item, etc.) then I would say "minimal HTML skills" would be good. If you want a completely custom site from the ground up then I would say advanced HTML and PHP skills would be needed.
1) Adding pages is done by creating a page in the "Page Creator" module, so that part is easy.
2) To customize the index you would customize the skins/SkinName/index.tpl file (HTML template with Smarty tags)
3) Profile page is controlled by the "profile" templates - i.e. skins/SkinName/profile_index.tpl
95% of everything is controlled by templates, so if you know HTML and CSS you can do a lot.
Hope this helps!