If my computer doesn't recognize the memory I installed, is there anything I have to do to tell the computer that it is installed?

No. RAM is a basic system component and you will not have to do anything to tell the computer the RAM is installed. First, reseat the memory. Check to make sure you have the correct module for your computer. Try reordering the memory in the sockets. On a Macintosh, try resetting the PRAM. If you need further assistance, please contact us.