Apple PC Compatibility Card 12-inch card - Manual (Page 23)

9 Installing the Card in a Power Macintosh 7200, 7500, or 7600
9 Pull out the port access cover behind the first expansion slot (the one closest to the
center of the computer).
It’s recommended that you install your PC Compatibility Card in the first
slot (the one closest to the center of the computer). But if a card is already
installed in the first slot, you can install the PC Compatibility Card in
another slot.
Push the port access cover in gently with the finger of
one hand while pulling it straight up with the other hand.
(back of computer)