I'll do this from memory, mine was a Wallstreet but I think they're much the same. I'll assume you've got the right memory.
Pull out both cartridges, battery and storage (CD or Floppy)
There are two slide tabs up under the top case you'll feel once the modules are removed, at the front edge of the keyboard. Slide them back and the keyboard releases on the front side. Pop it up and pull it towards you and manipulate it out of the way (upside down). You don't need to disconnect the ribbon cables but you can if you wish.
Remove the aluminum cover, two screws, there's a little wire handle to pull on the front side. It lifts from the front, there are little tabs that hook into the case on the back.
If I remember right you'll have to remove the HD, it's in the way, it's only one screw. Tug up the left hand side, there's a connector there, pop out the drive.
Then gently pry up the processor board from the right side, there's a connector there.
If I remember right there's a memory module on the upper side and another on the lower side. If you only have one installed the empty one is probably on the bottom.