Is it difficult to install a portal window?

I like the look of those round or six-sided windows, usually located next to the front door (mine will go there and should help to illuminate the stairwell). The wall I want to put it in doesn't have an electrical outlet but being next top the front door, there are light switches and the porch light on the outside. I've done quite a few 'do-it-youself' projects including some electrical, such as replacing fixtures, embling (including the wiring) a chandelier and replacing light switches and electrical sockets. Is installing the window something I should be able to do? Does anybody know where I can find installation instructions online?