I have a beige tower, and this is how you do it.
Press the teal button on the top. This will let you remove a side panel. Flip the tower over on its side and flip up the two black latches. Use the conveniently shaped handle and flip up the part that you unlatched. You can now see the PCI slots, etc.
Note: for HD stuff, you only need to remove the side panel, but for memory, pci, cpu, etc you need to unlatch the inside part. HTH