Welcome to the new world of social networks. After a couple of less than successful attempts at dethroning Facebook, the reigning king of social networking, Google has finally introduced a very slick, well designed and powerful social network that's similar enough to Facebook that people get it quickly, but different enough that it's interesting and not a rehash. Me? I really like it so far, but it's still young so we'll see how it works when there are 10x the current members and they've continued to tweak and refine it.

You're right, too. When Google first introduced Gmail, I remember there was a little "Invite" box and a count-down that limited how many people you could add. In fact, heck, it's still there on my Gmail interface, on the lower left corner, and I can only invite 50 people until I have to wait for it to be "recharged"...

But on Google Plus, it's rather a mystery. Here's what I have figured out, however: if you add someone to one of your Circles (the Google Plus equivalent of lists or groups) by specifying their email address, they'll eventually get an invitation to join Google Plus. They'll already be in your Circle with just an email adds, but they'll be more in the Circle once they're fully on the site too.

One thing I have also heard is that everyone who is going to be invited to Google Plus will need to have already set up a Google Profile, so if they don't have one, you might need to encourage them to do that first. Check at profiles.google.com if you're not sure.

Let's jump in. In Google Plus, you want to click on the Circles button along the top of the page:

Once in Circles, you'll want to click on "Find and Invite", as shown:

Google is apparently digging into my Gmail address book to find people it thinks I might want to invite. I might have sent email to 497 people in the last year, but it doesn't mean I want to be friends with them all... Instead, scroll down just a little bit and you'll see a few of the people on your recommendation list and - most importantly - the "Add a new person" button:

(by the way, see how there's a tiny circle below Dan Murray's name, but not one below Robert Scoble's name? That means that Dan's in a Circle of mine while Robert isn't. It's a subtle but useful bit of feedback to recognize)

Click on "Add a new person" and it'll prompt you for a name or email address:

Since I am about to invite my friend Marv, I'll copy and paste his email address in the box provided:

I press Return (or Enter, whatever your keyboard shows) and it asks me for a bit more information:

Enter their full name, then click on "Select Circle" to see a list of all the G+ Circles you've defined. I pick "Friends" for Marv and click on the blue "Save" button...

That's it. He'll get an invitation to join Google Plus as soon as the backlog is cleared out. For some people it's currently taking a few days or longer, but as the site opens wide, I expect that'll drop down to a few hours or even less.

Hope that's helpful. There's lots to learn in Google Plus, so let's go!