You can use the XenForo Manual, post in the Community Support forums, or open a Support Ticket.
2. What do I do if I think I have found a bug?
Check that the problem doesn't occur on an unmodified style with no add-ons installed. Also, do a search first and check in the Resolved Bug Reports forum as it is possible that the problem you are encountering has already been reported. If it hasn't, please create a thread in the Bug Reports forum.
3. I have a license yet I still can't post, view or download attachments in the Customer forums.
Ensure you have associated your forum user name with your customer account. If you used the same email address for both accounts, they will be synchronised automatically. It can take up to 10 minutes to process.
For any other questions you may have, check the Main FAQ, the Pre-Sales FAQ, or the XenForo Manual.