Here's the video I used to learn to tie a bowtie for my wedding:
In the end I guess I did a passable job but never really got the knack. The last step is the hardest, the part where you pull the second bow through the loop behind the first one.
Here are some pictures of my dad helping me with my bowtie. (He does not know how to tie bowties either.)
I'll probably get some more wedding photos in here at some point. Seems like I should probably post some with the bride in them.