It will then bring up your browser to this page:
You can click the link or wait for it to re-route you to the site (I let it do it automatically).
Once at the site, look for PLUGINS INDEX.
There will be three and they are normally straightaway at the top of the page. Here's what they look like:
If a plugin has been upgraded, it will show that that as well so you don't download an old plugin. Just read through carefully and download the plugins you think you'll use.
See, simple! No more running all around the internet for Paint.Net plugins.