Can i still use my?

Question

39 cent postage stamps even though they raised the cost of postage stamps to 41 cents?

Answer 1

Yes, you just have to add the 2 penny stamp also to equal the correct postage amount.

Answer 2

Were you born sometime after the last postage increase? :)
(first class postage went to 37 cents in 2002, then 39 cents in 2006)
Yes, you can use 39 cent stamps, but you will need 1-cent stamps to bring the total up to 41. You can use the old stamps on postcards, but that would be overkill because postcards are 26 cents.