A simple and quick guide on how to use Filter Forge.
1. Open any image in Paint.Net
2. Go to Effects -> 8bf Filter -> Filter Forge 7 - > Run Filter
3. Now you see Filter Forge 7 window with your image in it. You can choose any filter from the upper left area. But I'd recommend you to start with Watercolor Painting: you can find it in the Effects -> Creative folder or with the help of the search line.
4. When you found an appropriate filter or just found Watercolor Painting -- click Apply. You get a result like this:
By the way, nice to meet you. That's me and my family.
5. When you are bored to use all the preinstalled filters, go to our Filter Library. There are 12k+ effects and textures to explore.
That was the simples way to use Filter Forge. But it also can generate procedural textures, patterns, it has tons of frames and you can create any type of the filter yourself usinf the Filter Editor (don't be shy, it is node-based).
If you have any questions, feel free to ask.