To add BBPress Forums to your WordPress site you will want to visit your dashboard and find the plug-Ins tab on the left Navigation. Once you hover over that choose Add New from the options.

Next you will want to type in BBPress to the search box.

This will bring several BBPress related items, but the first should be BBPress itself. Choose the instal option and follow the prompt to activate the plug-in.

Once you have activated the plug-in you can find access to the settings from the Forums tab in the left navigation:

Add forums and enjoy!
For more info and support visit:
http://bbpress.org/