1st time flayer needs some help!!!?

[Lovely]

I am studying aboard to Africa from the states and this is going to be my first time on an airplane and buying tickets, so i really don't know the process of the whole thing, i don't know what website to go to so i can buy my ticket, i seen ASAP TICKETS Services, which has very cheap tickets, but i also heard bad things about that one, or how does buying plane tickets work?? please help !!