Someone else has chosen to share snippet files with you, and you're ready to use them.
Upon receiving one or more snippet files, you can integrate them into your own copy of Visual Studio using the Code Snippets Manager.
The Code Snippets Manager is accessed through Visual Studio's Tools Code Snippets Manager menu command. The Add button on the form lets you add an entire directory of snippets to Visual Studio, while the Import button adds a single snippet file.
The quality of the code snippets you receive from others may be limited by the skill and trustworthiness of their developers. Caveat emptor.
Recipes 2.1, 2.2, and 2.3 provide additional information on code snippets.