PhateX1337

Hey everyone,
Let me start off by saying sorry if this question has been asked before I tried searching for relatic topics but couldnt find any. I just got an x50v and I downloaded the AIM UK for it, and when I open that program up it says "New User" in the upper right hand corner and then when I try to open the buddy list or anything it says that I must first select a username. Does anyone know what I can do to select a username, when I try to go to the New User in the top right it just shows that name with a check mark by it and I have found no way to give it my AIM account name.

Thanks again,
Brendan