Dell OptiPlex Micro 7010 Owner's Manual page 33

2. Align the tabs on the side cover with the slots on the chassis.
3. Slide the side cover into place towards the front of the computer.
4. Tighten the thumb-screw (6x32) that secure the side cover to the chassis.
Next steps
1. Follow the procedure in After working inside your computer.
Side cover 33