Hi Sarah P,
Well, it’s pretty easy to activate/open the Snapchat filters. When you are at the Snapchat camera screen, press anywhere on the screen for few seconds and the filters will automatically pop up on the screen. To have fun with more filters, just swipe your screen to the left.
If you need more help on How To Use Filters On Snapchat, click on the link highlighted in bold. It has more instructions on how you can use and record videos with the Snapchat filter, How you can avail more filters by enabling in the app settings, etc.