I'm confused, that's my normal state, but are you going to have an open valley or a shingled valley? Are you using shakes or shingles?
If this is your first time, an open metal valley is probably easier. A W valley would be best, it has an inverted V in center, not only does that alleviate water running across valley and under shingles, it helps you center it in valley. Here's a pic and some more instructions on installing. Note that shakes and shingles need different widths of valley and under flashing.
[CENTER][FONT=Comic Sans MS]Measure twice, cut once.[/FONT][/CENTER]
[CENTER][FONT=Comic Sans MS]Look at the nail, not the hammer. Watch the fence, not the blade.[/FONT][/CENTER]
[CENTER][FONT=Comic Sans MS]If you hook your thumb over your belt you won't hit it with the hammer or leave it layin on the saw table.[/FONT][/CENTER]