So you have just found out you have to make a class site and and are freaking out a little bit.....
This video shows a couple of tricks you can use to get Google Sites working the way you want it to.
Buttons are only images, don't let the word "button" confuse you. Button's allow you to navigate within your Google site without being limited to the Ugly Horizontal or Side navigation bars that Google tries to force on you. For more help on buttons see here.
Using Tables helps you control your Google Site.
When everything is placed neatly inside of tables, Google is unable to move things in weird ways or put things out of alignment. It also gives you far greater control over the spacing of your site.
Using HTML seems scary
Using the HTML can be pretty intimidating, but you don't have to be able to understand it to find the area's you are looking for. Using Command-Find or CLTR-Find on your computer to fast find sections within the HTML can help you fake your way through a whole page of HTML easy.
For help with HTML check out this HTML site help sheet here