No apology needed. Well, the easiest way would be to find out what model computer its going in (if its a brand name like HP or Dell) and look it up in the computer's manual. If its a clone or custom machine, then the easiest way would be to find out the model number of the system board by taking the cover off and looking onto the main board (the largest board where all the smaller boards and wires go onto). There will likely be brand name and model number on it. Might be a brand like Asus or MSI or Gigabyte..etc. The model number is usually not too far away.
Once you have the name and model number, I'd go on the manufacturer website and look up the product manual and in there will be the memory configurations. If it matches the RAM you have, then all is good.
By the way, there are software like Belarc advisor that will attempt to read the memory configuration of your computer but I dont always trust them as they have come up with data that was not right before.