How can I open AIM on my MacBook?

I just bought a MacBook yesterday and, as I’ve been a PC user my entire life, I’m having some trouble figuring things out. The current issue is that I just downloaded the AIM 2.0 for Mac and everything was successful…except I have no idea how or where to go to actually find and open it. I’ve been searching around for about half an hour and all I can find is the install icon. On PCs I would download something and when it was finished installing it would automatically give me the option to open what I just downloaded…does Mac not have this or am I just missing something completely? I’m not all that technologically literate (especially not for Macs) so I’m getting pretty frustrated and am starting to think that getting a Mac was not the best idea I’ve ever had. I need help :(