BuddyPress.org

1.) Are you using forums for groups, or site wide forums?
2.) Did you make sure the discussion forums box is checked in dashboard/buddypress/components.
3.) If you used forums for groups you have to create a group first. This can be done in the front end under groups as long as your logged in. After you created a group, then click forums and create a topic.
4.) If your using a site wide forum you need to go to dashboard/forums/new forum and create the page and name it, then publish it. Then it will show up in the front end under your forums navigation. Just name your Topic, give it a description, and at the bottom of the screen click submit.
5.) You may also need to create a custom menu in dashboard/appearance/menus. Create a new menu, name it, save it. Where it says Theme Locations Primary Navigation click the drop-down menu select the name of the menu you just created and click save. Below you can now select your all your pages, click the check box’s then click add to menu, and in the left you can drag them to the order you want to appear on your navigation, then save the menu. I hope this helps!