As mentioned previously, Paint.NET is free. This means that there is no tech support of any kind.
So, where do you go if you run into any problems or need help? Under the Help tab in the menu bar, you will notice that there are several sections. Three of them that will help you the most are mentioned in the following sections.
Help Topics (F1) will take you to the help topics website found at http://www.getpaint.net/doc/latest/index.html.
This web page is a one-stop shop for everything about Paint.NET, starting from installation to details about every window in Paint.NET.
Forum is an excellent, well-maintained source of information about everything that has anything to do with Paint.NET. It has years of archived postings of people helping each other with the program. There are probably no issues that haven't been dealt with here. It's all searchable; so if no help topics seem to give you the answer you are looking for, it is most likely that you will find the answer here. The forum can be found at http://forums.getpaint.net/.
Tutorials is the best place to go if you want to really stretch yourself with Paint.NET. There are lessons and tips galore. It is here that people upload projects they completed with Paint.NET, and then they break down exactly how to recreate them. It is a great place to go to get inspiration. The site can be found at http://forums.getpaint.net/index.php?/forum/18-tutorials-publishing-only/.