So this may seem like an insanely stupid question and I feel like I'm severely over looking something obvious but I have a bunch of TF2 items that I think I wanna try to sell. So... first I want to see what the going rate for these things are on the marketplace but I actually have no idea how to access it?

I updated the game and launched it and poked around but only saw option for the valve run store. Can someone help my bumbling idiot self figure this out?

It's under the Community tab in Steam, in the dropdown menu.

Open Steam, hover of the Community tab, click Marketplace in the dropdown.

http://steamcommunity.com/market/