Community testers have a crucial role on manjaro distribution, after manjaro updates are tested by the Team community can then step in and report any issues found, Being a community tester is very easy you need a forum account and some free time to give your input.
Head to announcements section of the forum and choose the branch that you are on and want to give test input, default is stable, choose the latest announcement, make sure your system is up to date and report your findings.
If you have a fix or workaround then make sure your post those also, as you would help the team get to a solution faster.
The testing section is for you to help test and improve the distribution, is not a place for personal support however if your issue gets resolved it will also be fixed for everyone and not just on your personal machine, so leave out anything that is not relevant to the issue or messages similar to (this update everything went well) as those are not going to help fix problems and take post space for users reporting real issues.
If you are a experienced Linux person then you can skip this and head directly to manjaro Gitlab and report your issues there or even send a PR.
There is also a quality assurance section were you can give your input and help improve software.