I found that if I click on the name and or picture - it brings you to their page ( within our group) and then you can invite that way. Otherwise I think you have to email, provided you have that information available. It is all so new - I feel like I am stumbling around it a bit.
Very cool stuff! Diggin' the Papa Roach, love Jimmy Eat World, and thanks to you that was the first time I've heard Johnny Depp do "My Friends" - nice. I actually saw the original Sweeney Todd with Len Cariou and Angela Lansbury. I've had Time Burton's version in my Netflix queue since forever - gotta get that baby delivered!
Adding music is fairly intuitive unless you have to add something from more than one folder on your hard drive. Then, the navigation gets a little rocky. I screwed it up several times before I got my first batch of songs up. It is learnable with practice, though.
I didn't think the navigation was very bad at all, but then I'm pretty computer savvy (not as much as I'd like though). I'm one of those pesky people who doesn't read instruction manuals. :P But yes, practice does indeed make perfect.