In the Settings section on your phone, you should have the capability to turn on your location. You will need to enable this in order to use Geofilters on Snapchat. Where these are located will depend on what type of phone you have. Android users will find it under Location, while iPhone users will find it under Privacy. Once you spot it, simply allow your phone to access your location. This is vital for the app to work, as Geofilters need to find events local to your area.