trying to understand ohms.

Can anyone try and explain the theory oh ohms to me as far as getting the right sound and setup for a amp and subs. This kinda has to do with my other post with the Alpine 1507 amp and JL W3s. Is it best to have lower ohms from the subs or exact ohms? My amp (2 channel) runs 4 ohms bridged and 2 ohms per channel if your running 2 channels. I have a box for 3  12" subs and the guys who was running this setup had three W3s so im just trying to stick to that. After using a search engine to do some research, i found some wiring diagrams for subs on the Mobile Authority website. I kind of have an idea now about how it all works. Im just not sure what is optimal... if i bridged the amp(4 ohms) and was running 3 DVC subs at 6 ohms a piece, would it be better to hook them up without utilizing the second voice coils to have a 4 ohm rating, or hook both voice coils on all 3 subs up to have a 1 ohm rating?? Hopefully this doesnt confuse anyone. Im trying not confuse myself!   Any help would be great. Thanks ~Ed