I can speak from some very relavent first hand experience here:
Helicoil taps are NOT LIKE ANY NORMAL TAP. I used the wrong type and didn't realize until it was too late. They are completely different. Helicoil taps can ONLY be used for helicoiling and only helicoiling taps will allow the coils or "threads" to work.
You need to buy a "Helicoil kit". They can be bought via Driftmotion or some hardware stores, possibly an auto parts store. Personally, I would buy the kit from Driftmotion. They give you everything you need, just double check the parts to make sure they all seem to line up.
Again, USE ONLY SPECIFIC HELICOIL TAPS. There is NO tap other than a HELICOIL tap that can work. Buy them together in a kit that will contain the coils, tap, coil inserter and instructions.