[AccessD] Creating a Login form & check PW...how?

Easy one for y'all...(A03 by the way)
 
I'm trying to add a login screen to a current db, so that I can divide users into three groups. Depending on your group, different buttons will be enabled/disabled. 
 
So far I've got a table (tblUsr) where I've got the individual users...txtUsrID, txtPW, txtSecLevel. I have a form w/they can type in their ID and PW, but I'm having trouble figuring out how to check that they have entered the correct PW.
 
I figured this would be easy enough, and I thought I did it before, but I'm struggling here.
 
Thanks! 
JClark
 
PS...I haven't been out here much, because my programming duties were scant, but I've been assigned a couple more programs, so I'll probably be a pain again, until I get my wings back ;o)
 
 
 
 
John W. Clark
Computer Programmer 
Niagara County
Central Data Processing