Here are some tips on how to install a door casing. The materials/tools you will need are as follows:

1) Trim
2) Mitre saw (or hand saw)
3) Nail gun (or nail and hammer) *I use 1 1/4 inch nails
4) Tape measure
5) Caulk (and caulk gun)
6) Wood filler
7) Paint/paint brush/roller
8) Pencil