How do I upgrade RAM in a Dell Optiplex 7080 SFF?

Very easy — you only need a small Phillips head screwdriver. The 7080 SFF has a tool-less cover, but you still need to turn the thumb screw with a screwdriver (or your fingers). Once the lid is off, the RAM slots are right there, clearly labeled. Push the new stick in at an angle, then press down until the clips click — just make sure you buy DDR4 SODIMMs (laptop-style RAM), not desktop sticks.