You have 2 easy options. First you need to be running pip from your scrips folder in the python directory.
Download your whl file and place it in the scripts folder where your pip.exe is.
In command prompt (windows) type:
#note the exact file path may be different but should look something like this. cd C:\program files\Python\Scripts
after you are in your scripts folder in command prompt you can then run the command:
pip install nameofpackage.whl
note if you have more than one python version installed make sure you are running pip in the correct directory and if you have 2.X and 3.X installed you may want to use pip3 instead of pip
For windows users your second option here:
like the first option make sure you are in your scripts folder in command prompt then you can run a command to install your whl file on a local directory:
pip install C:/path/to/dir/with/filename.whl