Go to a court that can properly help you. This will most often be a Family Court, but may be a District Court if there is no Family Court in your county. You can file in a court where either you or your abuser lives. If you have questions about where to file for a protective order, contact your local police.
Here is a brief listing of current Family Division courts where you may get a protective order. You can find a complete updated list on the NH Court website.