Calm thineself, dear newbie!
Go to the main lobby, first, found under the group tab in the green toolbar. (Also here: http://www.iwakuroleplay.com/group.php)
There is a green button at the top of the screen that reads "Create Group". Click on this, and then fill out the information in the correct spaces.
First, though! You should look at the other groups and see if what you want to make a group about doesn't already have a group for you to join. Avoid clutter and maximize on people with the same interests being in the same place.