To get to the filters on snapchat online follow these steps and you should be able to get to the filters on snapchat.
Go to the Camera screen in Snapchat.
Then Tap on a face! Now Swipe left to select the Lens you want to use.
Then Follow any action prompts that might appear.
Then last Tap the capture button to take a Snap, or press and hold on the capture button to record a video.
You should then be able to access the snapchat filters.