On the right side of your main page, find the 'My Groups' section and click 'New Group'

you'll get a window that looks like this: just fill in the name,

    set Membership to 'Open'

          Visibility to 'Visible'

    and leave the 'Force registration origin' field blank

that's it. you've made a new group.

you can change the Membership and Visibility options at any time from the left panel of the group's main page ->

and there are just a few more options that are worth taking a look at:

don't forget to change the avatar, then:

Once a few people have submitted Tabblo's to the group, you'll find these:

You can 'Feature' up to three Tabblos at the top of the page.

Remove Tabblo from Group

Add as Feature Tabblo