well on your mixer, there are EQ knobs i think, if not, you can get EQ units to suit your needs, basicly EQ allows you to shape the frequencies of your recordings...low(bass) mid and high freq.
reverb is to add ambience, not really a delay, it is more of a mild echo, which simulates a large room, hall, church type sound depending on what you set it to do, reverb will make a drum machine sound less dry and more real, vocals will have a greater presence and you can produce that surf rock guitar sound........just a few things you can do with reverb