Hi, Crimsiny and Oscaver! Welcome to the Playground

To make your sig, go to User CP (a link to which can be found at the far left of the brown bar near the top of every page), then click "Edit Signature" in the column of options on the left of the screen (it's the very first one). Note that your signature will not appear on posts you have made prior to setting it up (unless you edit all of them and select "Show your signature"), but it will automatically appear on all your posts after you set it up.