who

hi I just need someone to help me with one line of code in wordpress backend.

I have a new field in the 'wp_user' table of the wordpress database,

All I need to do is write some one line of code which will update that field with a value from $_POST

I am struggling now with this crap for a couple of hours... I feel like a retard and most likely am. But can anyone help me out?

Thanks.