To clarify, make a thread containing the gear you possess in the forum that best represents it. For example, if you want to trade your tippmann, you can make a thread in the mechanical markers forum titled "98 Custom F/T". In the thread you can list any mechanical marker you have and what you want for it. You may not, however, put an electronic marker you own in that thread. That would need to be posted in its own thread in electronic markers.
Seeing that you now have active infraction points, I would be sure to read the rules and FAQ completely before posting again. Another rule violation could earn you a temp ban.