Hi Raymo,
You need to follow Louie Atalasidi's tutorial on masks, and practice, practice, practice.
If you have trouble following, minimise your photo shop screen and Louie's tutorial until they both fit on the screen.
Then you can pause at any section of the tutorial so you can practice in PS.
Here's Louie's tutorial.
http://www.atalas.net/masks-for-photoshop
There's no way around it you have to learn it.
It's well worth it!
Cheers,
Justin.