The main Michigan Union computing site is in room B620 of the Union. To get there, go to the lower level where the MUG (main restaurants) and ticket office are located. Go past the Computer Showcase store and through the double doors. Just after those doors and immediately to your right, there is a knee-high gate in front of a set of stairs. Open the gate and go down the stairs. The site is at the bottom of the staircase.
You will need your Mcard to access the site 24/7.