Install vintage window and frame. How hard?

[PCowley9]

Hi. I'm a semi-handy chick and can follow directions--(?) I have a 1930's bungalow, the attic has an ancient plastic rectangular vent facing front but no windows. I REALLY want a window there for the cozy factor and bought a small 6-pane vintage window just a little bigger than the vent. The window is solid. Can I make a BASIC custom frame and yank out the crappy plastic vent? This attic is well ventilated and empty. I don't think my window will cause any ventilation problems. (Especially with me installing it). Can anyone tell me how to build a simple but adequate window frame to fit my window? Sealants, flashing? I'm clueless. I just want it to not be embarrassingly bad and damage the wall. Interior attic wall has no insulation, just 2x4s. Outside is aluminum siding, if these facts make any difference. Thanks for ANY help or direction!!

[pushkins]

The aluminum siding pretty well means your in for a world of hurt if you touch it. It cannot be manipulated like vinyl for obvious reasons.
The vintage window you bought, is it already in a frame or is it just a piece of framed glass ?

[PCowley9]

Old house, old window, old lady

Hi Pushkins-- Thanks for your reply. My window is just a window from one of those overpriced architectural salvage places-- it's six lights, the stiles, just one piece, about 18x24. And, I suppose the plastic vent I want to yank is just pushed into a frameless hole. I haven't pulled it out to check how it is 'seated,' so to speak, as just touching it caused a hunk to break off. Yes, the exterior is oldish white aluminum siding. The frame for my window doesn't have to look beautiful--it can be pretty primitive since it'll be seen from 30 feet away. Just don't want leakage issues. Thanks again!