Clicking on this link: https://www.stangnet.com/mustang-forums/ or clicking on the "Forums" navigation tab above, will take you to an overview of the available forums.
From there, you will see that it is broken down into discussion forums and classifieds forums for each platform of Mustang. Choose the appropriate forum for your year car from the discussion forms and go to the 'General/Talk' section. There is where you should begin instrocuding your car and asking about issues relevant to your car.
The technical forums are specifically for questions regarding a set of steps or instructions necessary to accomplish a job. All other questions particularly, those that ask for an opinion (even if technical in nature) go into the General/Talk sections.
Of course, classified and want ads all go into the classifieds sections.
There are a few off-topic forums sprinkled here and there and more of those will become visible to you as your account matures.
If you have questions or get stuck, hit up one our overpaid and under worked moderators. Their screen names are in GREEN. You can open a private dialog with them by clicking on their avatar and selecting "Start a Conversation".