putting a tap on a trailer

[mybaybe]

I have been told that I need to put a tap on this trailer. I go on rides and rallies with the American legion and some other groups and think it would be nice to have one on it but don't know how to do it, btw, I don't drink myself. I made this trailer last year. I took out the compressor, the freezer part could hold a baby keg plus filled with ice w/ the tap on the front, on the right side would be great. any help would be appreciated.
thank you.