The Basics: Filters are GreyHen's way of implementing blacklisting and whitelisting. To use filters, you will have to have an account on GreyHen - if you don't have one, you can sign up here.
Adding a filter: To start, go to the User Homepage and click "Filter". To add a filter, simply enter a search term (or a series of terms) in either the "Whitelist" or "Blacklist" field, and click "Confirm". You can also remove filters at any time by going to this same page and clicking the red X next to any single filter, or "Clear All" at the bottom.
Filter Function: Once your filter is in place, it will function without you ever knowing that it's there. It won't show up in your searches, but it will constantly affect them - we know that seeing your filters in every single search or URL would not give a great mental image or browsing experience, so they're designed to be low-key.