There is a guide HERE
To install your own libraries that might not be covered by that tutorial, place them in the LIBRARIES folded
Close out the IDE.
Go to the libraries folder where you placed then and simply unzip it but don't change anything.
Check the folder structure to make sure it is not lets say for example "Lib01_master" with another folder inside that called "lib01_master"
If it is remove the "_master from the inner directory and copy it to the main libraries folder and then deleted the now empty "Lib01_master folder"
Now restart the IDE and it should be listed in your libraries.
If you see any error messages in the lower console you could have made a mistake or the lib may have a conflict of some description.
Using the library manager of the IDE itself is the better option to add libs. as then they will often get the updates.
If I missed anything there Pert correct me as I know this is more your area.