Hmm. First of all, I have to find music, music that I can buy and legally use on the trailer. This took several days of cursing and grumping as the music I wanted couldn't be found and when I finally did find it, EXPENSIVE! Like $150 for a 4 minute song. All because of a little thing called licencing. Sheesh!
What I've discovered is a site called Audio Jungle. It's where composers can go and put up their original work and you can purchase it for a minimum cost. I paid $13 for the song I chose and I actually like it better than the original song I had picked out. Happy day and we're off to the races.
Next comes pictures. Again I struggled and cursed only to find that no matter where I went, if I wanted good quality pictures and videos, I was going to have to pay for them. Voila, iStockphoto seems to have a good selection, not too high of price and it's fairly easy to navigate.
Now I just have to mash the music and pictures together, hopefully with a computer program I already have. . .I'll get back to you on how that goes.