from user id to username

[Blue2000]

first of all am working on a game for vb called subber

i have made it so that when they submit it it will recode there user id into a table called "subberuserid"

but the problem i have now is in the display of subber i can only get it to show the userid and not the username. i have looked at the tables for private messaging and posts and i notice that all you have there is the user id aswell and not the username.

so how would i turn it from userid to the username?

thanks for you help