Here is a full teardown tutorial of the phone, but you only need to focus on the screen portion of the video:
https://www.youtube.com/watch?v=TVvinBYCnGQ
It is easier to replace the screen that already has the frame on it, because it eliminates the process of having to adhere the screen only portion to your old frame. I personally like the frame/screen combo rather than screen only, but it’s a little more expensive.
NOTE: The repair guy in the video uses metal to get the back off. Do not use metal to get the back off. When you’re in the process of getting the back off, don’t push your tool in too far or you’ll break those flexes on both sides of the phone.