Just copy the font file directly to the folder C:\WINDOWS\FONTS.
There are two ways:
1: Copy the downloaded font to C:\WINDOWS\FONT\, and you will be prompted to install it automatically. Just click Install.
2: Start-Programs-Control Panel-Fonts, click File-Install Fonts, and then find the folder where fonts are downloaded, and you can install them. In fact, the easiest way is to copy the font file directly to the folder C:\WINDOWS\FONTS.
You can find the downloaded fonts from the Internet yourself, and I can also send you some commonly used fonts.