The first few times you visit the forums it may be confusing trying to navigate through the different forums and topics. The easiest way to move back and forth inside of a forum is to use the back button on your browser or use the links found at the top and bottom of each page.
For instance, if you look at the header above this post you will see a long thin tan strip that contains the navigation trail leading to this post. It will look something like this; Board index>> General Topics>> How do I use this Forum?
You can click on any point in the navigation trail to move to that point. If you want to jump to a different forum you can click on the "Board index" in the beginning of the navigation trail then click on the forum you wish to enter. You can also jump straight to it by selecting the respective forum in the "Jump To" drop down menu at the bottom right corner of the page.