You didn't read the rules.
GO READ THEM NOW.
You're in one of our 'new user' usergroups, and as such, have limited privileges. For users here less than 30 days, you may not make any threads, nor have a signature or insert images in your posts. For those here longer than 30 days but less than 90, you may post pictures and have signatures and even create threads, but not in the Marketplace.
Signatures - this is more of a earned thing, and will help me differentiate between noob users and those who have been here for more than 3 months.
Thread creation.
First 30 days - You don't need to be making threads. You need to be searching and reading and posting and conversing with the rest of the forum.
First 90 days - You don't need to buy or sell anything in the Marketplace. I don't care if you have a warehouse full of cheap parts, you're not selling here until your 90 days are up or until you've established that you're willing to take a financial risk* by selling/buying here.
*via the purchase of a Premium Membership or Advertisement/Vendor package.