Download the font file from a trusted source
Unzip the font file if it is compressed
Locate the font file, usually .ttf, .otf, or .ttc
Install the font on your computer
Windows: right-click the font file and select Install or Install for all users
Mac: double-click the font file, then click Install Font in Font Book
Close and reopen Photoshop
Select the Type Tool in Photoshop
Open the font menu and choose the installed font
Restart your computer if the font does not appear