[Can't get plugins]

I installed it in my documents by accident.

[Can't get plugins]

I don't know if this is in the right place, but I don't know how to use plugins. My folder for Paint.NET looks like this:

Please can someone tell me how to use them?

[What's wrong?]

When I try to uninstall or repair the new version, it says I'm missing a .msi file, but I thik I deleted it then later I emptied my recycle bin. I have the .NET Framework still installed. When I try to install another, it says I already I it installed. Please help. :?