making things look old

[toxic-divinity.livejournal.com]

hey guys, i hafta do this family history deal for a history project. one part of it involves writing a journal loosely based on a real persons experiences immigrating. My mom has some old envelopes of letters sent to the house my....great grandfather? built and they have a stamp and stuff on them. Soooooo I kinda wanted to maybe replicate an envelope and stick it in a page of the journal (i decided to make/bind my own journal). I was wondering what would be the best way to make an envelope brown and very antique looking. I didnt give the memories a real good look, sorry, but I dont have time. I didnt really see anything that seemed like it would help me.