There are various forums for getting help. The most productive is to send email to the axiom-developer mailing list. This forum is watched by many people and someone is likely to answer your question in a short time. Be aware that Axiom support is a strictly volunteer effort so adjust your expectations accordingly.
If you encounter a bug you can post it to the axiom-developer forum.
Be aware that if you don't include which system you are running,
which release of Axiom you are running, and a reasonable console
log that shows the bug then you can expect to be asked for those.
It is nearly impossible to debug a problem without this information.
In addition, if you feel it necessary, you can copy me directly on
the email. Send it to Tim Daly.
This won't change anything about the response though as I get all of the
emails that go to the list.
There is another list, axiom-math,
intended for math related questions rather than developer related questions.
If your problem is about how to compute something or ideas for new math
or other non-developer questions, feel free to post them here.