Download Aspire 5720 User Guide. Extract the .zip file and open the User Guide Acrobat File.
You can finr info on Installing memory on page 75
ftp://ftp.work.acer-euro.com/notebook/aspire_5720/manual/EN.ZIP
Follow these steps to install memory:
1 Turn off the computer, unplug the AC adapter (if connected) and remove
the battery pack. Then turn the computer over to access its base.
2 Remove the screws from the memory cover; then lift up and remove the
memory cover.
3 (a) Insert the memory module diagonally into the slot, then (b) gently press
it down until it clicks into place.
4 Replace the memory cover and secure it with the screw.
5 Reinstall the battery pack, and reconnect the AC adapter.
6 Turn on the computer.
The computer automatically detects and reconfigures the total memory size
Regards
Mike