How would i go about hooking up three subs to one amp?

depends on the subs and the amp......need to know whether the subs are single or dual coiled and whether its 2, 4, or 8 ohms. then you need to know what you amp is capable of........need to know a lot of things before I can tell u how to hook it up.......

yea..definitly CANT tell until the specs are known of all the components

Ditto need to know what subs you have and what amp you plan on runing them off.. then we can try to make you a diagram.. otherwise good luck haha