I just switched over from a dell to a macbook yesterday and i dont know what the hell im doing! but i got some help setting everything up yesterday and limewire was working perfect and today its not!

It opens and asks me if i want to upgrade to pro and when i say no it stays open for a second or 2 and then closes immediately! idk what to do i have moved every piece of limewire on my computer to trash and emptied that(i think that is how u remove programs?)

ANY HELP WOULD BE GREAT!! and please help me step by step! ive never owned a mac until yesterday!!
THANKS