Download the precompiled bootable .iso version.http://www.memtest.org/
Mount the .iso to a cd using a burning program. Nero or Roxio will work if you have them. If not here is a great little free program.http://www.imgburn.com/
Now in BIOS make your CD drive first in boot order so the computer will boot off of it. Then you can run the program. You will not be able to use the computer of course while it's running. By booting off the CD and not into a Windows environment the computer can check 100% of the RAM since there is none reserved for Windows.
I recommended running it overnight. To truly test 32GB you will need to run it as long as you can. 12 hours minimum. Any errors at all mean a problem. Even one.