Apple MacBook Pro (13-inch, Late 2011) - Manual (Page 46)

46 Chapter 3 Boost Your MacBook Pro
4 Hold the memory module by its notches and remove it from the slot.
5 Remove the other memory module.
Important: Hold the memory modules by their edges, and do not touch the gold
connectors.
6 Insert the new memory module in the slot:
a Align the notch on the gold edge of the module with the notch in the lower
memory slot.
b Tilt the card and push the memory into the slot.
c Use two fingers with firm, even pressure to push down on the memory module.
You should hear a click when the memory is inserted correctly.
d Repeat to install an additional memory module in the top slot. Press down on the
module to make sure it is level.