How do I reference a logged in user's ID in a URL?

I’m using WP LOGIN BOX plugin and BBPress. By default the WP LOGIN BOX redirects to wp-admin user profile but it has a place in the plugin settings to redirect to any link you like. I want it to redirect to the BBPress profile page. All I need is a simple way to reference the logged in user’s name in the URL. I thought this would be super easy to find but I haven’t found the answer yet. So basicly:

mysite/forums/users/”User’s name goes here called by php or whatever does the trick”

Please help. Thanks.