To report a bug on GitHub, you just need to create a new issue. If it’s something to do with the ClassicPress code, the link for that would be Sign in to GitHub · GitHub.
Reporting technical bugs well is not so easy. Generally you need to already know what’s going on behind the scenes, and provide clear steps for the developers to reproduce the issue. If what you’re reporting is a plugin conflict, or something else that won’t be fixed in the core software, then GitHub is not the right place for that.
Here’s an example of a problem that was reported well, and then fixed a few days later, checking it off the list and closing the GitHub issue: Dashboard Notice lacks closing button · Issue #163 · ClassicPress/ClassicPress-v1 · GitHub
Most user issues don’t look like this: often there’s a good bit of investigation and clarification needed, like in the example @viktor posted. The standard questions like “who’s your hosting provider? what version of PHP?” etc. This is fine, and getting that clarification here in the support forums works really well.
So I think I agree here: even though we build ClassicPress using GitHub, most bugs and support requests should start here in the forums.
We’ll look at making this wording clearer in time for the v1 release. Thanks everyone for the feedback!