1. insert cleanly trimmed wires through back of plastic shell
2. insert sealing plugs over each wire, skinny end first
3. strip end of wires and crimp* connectors inserts (metal bits on stripped end of wire)
4. verify the crimp is holding solid and the wire won't pull out
5. guide sealing plugs into the plastic shell, and then pull wire through from the back until the connector inserts are locked in place
*you might want to get the correct tool for this
You should study the old connector to make sure you get the orientation of the metal connector inserts oriented correctly in the shell. Often there are locking tabs to hold the insert in place (which don't work if you are 90' or 180' out of whack).
I know this is late but crimping them in not the proper way to rewire the MAF sensor bracket. I know this because I learned the hard way. Crimping is good for electronics that don't need precise voltages, the MAF sensor needs precise and accurate voltage being sent to the other sensors. There fore soldering and heat shrinking is the way to go.