irishprncess210's Purple wedding

I need some desperate help. I want to make a monogram on my aisle runner. Thing is, I am not very computer savvy.......it took me months just to figure out how to put a background on my page. lol. How do you do this?? I do not have the first clue on what program to use or anything. And then how do I print it out large enough? I am baffled by this. Anyone who could help would be a saint to me!! Thanks girls.