Invitations/Save the Date-- How to make

I really want to make my own Save the Date cards and invitations. Only problem is, I have no idea how to go about this. I am not a computer whiz, as you could probably tell when it took my 3 days just to post my dress on this site. Anyway, I was looking for some help on how to get started. Is their a certain computer program thingy I have to get? What kind of paper is good?

Robyn