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PIP is included out-of-the-box in recent versions of Python, and you'll need Python anyway for PIP to be of any us, make sure you download the Windows x86-64 executable installer or Windows x86 executable installer, depending on whether you have a 32- or 64-bit machine.
Once downloaded, double-click the installer file.
On the first screen, select the Add Python 3.7 to PATH option.
Select Install Now at the top. You can see this will install a couple extra components: IDLE, a Python Integrated Development Environment; documentation on using Python, and PIP itself.
At this point the installer will do it's thing and run through the setup process.