i didnt add enough hops...

i didnt add enough hops to a beer that is currently fermenting. i still have extra hops. can i dry hop or whatever after fermentation? like say add them during priming?

You can dry-hop in the secondary or even late in the primary if you're bottling directly from there. Another option I've been hearing a lot about is steeping the hops in a pint or so of water and adding that to the secondary - or presumably at bottling time with your priming sugar. Of course this will still add aroma and flavor primarily, without a significant amount of additional bittering.

When I dry hop, I usually do it by
- Fermenting in my primary for 10-14 days
- Adding my dry hops to my primary, and leaving it for 7 more days
- Racking to secondary and letting it sit for ~14 more days to clear.

You can crash-cool at the end of the 14 day secondary OR you can add gelatin or finings to clarify the beer if cloudiness is important to you (you didn't mention what style this is).

https://www.homebrewtalk.com/showthread.php?t=55721
This is a great thread that came up recently on the "hop tea" that Trencher talked about.

G'luck!

When you dry hop, do you sanitize the hops in some way? I've wanted to do this with my pale ales, but I've been pretty worried about introducing an infection.

Hops have natural antiseptic properties. I've never altered them, just thrown them in "dry".

If you are worried about it, the easiest way would be to take a small glass jar, pour your dry hops in (I usually use .5 or 1 oz, but have used as much as 2 oz before) and then add ~2 oz of vodka to it, just enough to dampen the hops.

Let the vodka steep for 10 minutes and it should kill any "bugs" and then pitch it into the fermenter (including the liquid). The vodka should be in such a small amount that it should have no discernable effect on taste.

If you're looking to make the brew more bitter try a hop tea and add it to the secondary.