'DIY' Invitation question

Hi everyone,

I appologize in advance if this is a pathetic question, but here it goes anyway!

DIY invitations: people on this site have some beautiful DIY's. But how and where do you get this stuff??

Are there good websites or stores for the stationary that you can suggest?

And what about the fonts?? Or are they just already on your computers that I just have not looked at because apparantly I have no clue about this stuff

If you DO know, I would greatly appreciate your advice! Thanks!