Weather stripping is easy if you get factory pieces.
Remove the old strip. Clean the surface well and remove any grease or gummy stuff from the sheet metal. I use rubbing alcohol and paper towels.
It helps if you have a buddy to hold the stuff so it doesn't flop around. Don't stretch the stuff or pull it as you install, other wise you will wind up with too much left over on one side or as the stuff shrinks back it will unglue itself.
Good Luck,
Jim Henderson