To access and be able to post on the state forum pages you need to edit your profile. To access your profile, just click on your screen name--that brings up your profile page. Select the edit prompt (even if you have already made a profile, this prompt should appear--you can make changes to your profile anytime). When your profile is in the edit mode, there SHOULD be a prompt which allows you to put a state flag on your page. Select your state. Conclude your edit. Your state flag should now be on your profile. When you click on that flag, you will be brought to that state's page. You can visit any state's page anytime you want via other freeper's profiles, btw, just by clicking on the various state flags as they appear on other freepers profiles, but I'm pretty sure that you can only post messages for the state in which you have chosen to be a member.
In order to return to the main forums from the state pages, you will probably need to use your browser's history marks. I've made it easier by making FR's news forum the homepage on my browser.
Try it out. If it works, post a message so I'll know you found it okay. If you still have problems, let me know.