The instructions for manual installation on the https://www.arduino.cc/en/Guide/Libraries are telling you how to find the right location to put the unzipped folder. Once you have the right folder, you cut and past the files. That’s it.
To update libraries, the easiest way is to delete everything in the library folder and re-download.
Can you clarify what you mean by “stuck” by posting screen shots of what you’ve done and the errors you’re getting?