Create a GitHub profile. You may want to ensure that the email address you used to set up your account stays private. To do this, go to the Emails section of your profile settings. Configure it as you see below. Copy/paste the 0000000+userName@users.noreply.github.com address somewhere, as you will use it later when configuring Git.
If you already have a GitHub profile, use that for now. Eventually, you may want to migrate your portfolio repository to its own, separate GitHub account, but that can be done easily later on.
Only after installing Git, add the contents of .gitconfig from this Gist (between the SNIPs) to your %USERPROFILE%\.gitconfig. Change userName to your GitHub username, and change 0000000+userName@users.noreply.github.com to the private email address provided by GitHub. You can just use your personal email address here, just know that people will easily be able to connect your personal email address to your account.