You should have gotten the Tow package install directions in the glove box, which shows what comes with it, and where things need to be installed.
'04+ MY trucks only need one relay installed, the remainder is good to go.:
If you did not get the directions, drop me an email via my profile, I can send you the PDF of the '06 trailer tow install directions ( also have the '01 version in case someone needs that ).
I went with the Reese Brakeman ( think that is the correct name ) ctrl'r for my '06. No leveling of the unit required, and it unplugs for storage in the glove box if you want to":
Few more install pictures in the interior album in my gallery, if you want some more options.