To upgrade or replace faulty memory, first you must find out what memory you are currently using. This can be done a number of ways.
The first way is to look in your motherboard's user guide, which can be found on their website usually. The manual will tell you what memory to use. The second way, is to use the task manager in Windows 10 (If you use Windows) to tell you. Finally, you can go to www.crucial.com and input your PC's make and model. They should tell you what you need and how much.
ONCE YOU'VE PURCHASED THE NEW RAM
1. Unplug your PC
2. Open the case
3. Locate the old RAM
4. Remove old RAM, making sure to depress the clips on the side of the memory holster
5. Insert new RAM, pressing hard until it clicks into place
6. Close PC case
7. Plug in computer
8. Turn on computer and verify the OS is seeing the new RAM
Please note: No person or company paid me to say anything about any of the topics above. These are my opinions and what I have observed using the program personally. Your experience may vary. I am not responsible for any data loss that may occur. Use my guides at your own risk.