How is that done, can I get some picture examples?:o

You might find some information on the following sites to be helpful to you. I hope that you do. You also might find a book on the subject at someplace like Menards, Lowe's or Home Depot. I am sure that a public library would also have books that would be helpful to you.

Framing For A Window Rough Opening (http://www.hammerzone.com/archives/window/new/ro_framing.htm)

Framing You Can Live With | DoItYourself.com (http://www.doityourself.com/stry/framing)

Hometime - How-To - Project Help - Windows & Doors (http://www.hometime.com/Howto/projects/window/win_4.htm)