Because you need to have a certain number of posts before you can start a new thread. This is to discourage spammers, including, but not limited to supply siders who think the purpose of these forums is free advertising for them.
So, either post in a pre-existing thread in this section, or go make a bunch of posts before introducing yourself.
So, either post in a pre-existing thread in this section, or go make a bunch of posts before introducing yourself.