many noob responses....
the easiest and best way to get power inside the cabin is from the fuse box. if you look, there are 5 accessory terminals (3 in the middle in a row, and 2 on the top side by side)
simply crimp on a female spade terminal to your power wire, and hook it to one of the accessory male spade terminals. of the middle three, one is all time hot, one is ignition switched hot, and one is light switched hot. I dont remember right off hand which is which, but im almost certain the one of the leftmost side is light switched hot (have my gauges power wires ran there.) you can use a simple multimeter to measure 12VDC and find out for sure.
this is the correct way to power accessories. Remember to use a fuseable link.