How do I restrict user access to plugins?

I have created a new user role in my functions.php and set up booleans for each standard WordPress capability (as listed on [the WordPress Codex][https://codex.wordpress.org/Roles_and_Capabilities#unfiltered_upload]. So far, things are going great!

I’m also using three plug-ins I’d like this user to have access to these plugins as well (Nextgen Gallery, Contact Form 7 and SEO Ultimate). How do I do this? I don’t know what the capabilities of these plugins are, or where to find them.

TL,DR: I want to set capabilities for a user role, but don’t know the capabilities of the plugins NextGen Gallery, Contact Form 7 or SEO Ultimate).