Helen, unless you have a real unusual situation, installing entry doors is not difficult. A good place to start is by checking all the home improvement programs on TV. After you have watched it a time or 6 on various programs, you should have all the answers. Removal of your old doors may be more of a problem. The tools that you will probably need are reciprocating saw, drill, 4 foot level,hammer, shingles for leveling, 2 foot level, caulk gun and caulk possibly a door hardware drill bit set and I'm sure I missed a few. You might also search the web for home center's sites or door manufacturer's site that have pictures. Written words are good but a picture is worth 10,000 words. Figure how and when you are going to install a screen/storm door also and what hardware you will need for that. It is generally easier to do both at the same time, unless you have to paint the door casing or finish a wood door. The prehung steel or fiberglass doors are great and usually come with instructions also. Be sure you check the instructions for anything different about installation of your particular door.