Why do most of my threads have a red x next to them and when I click on the x it tells me that my thread is locked? Why would it be locked?

it is closed by moderators, perhaps it is not necessary or it is not relevant or it has already been answered. you must read the other threads first because they may be existing threads with the same contents already. you may pm moderators too to know what really happened. if they were answered already the mods will close it right away to avoid flooding.