It's simple to add your location to your profile so it shows up beneath your username beside your posts. Newly registered members are unable to do this until they've posted at least once and had their user account verified.
Firstly you need to go to your user control panel, which can be access by clicking on your username at the top right hand side of the forum page, and choose 'User Control Panel' from the drop down box.
You will be taken to the following page where you just need to click on the 'profile' tab along the top.
You then simply type your location in the space provided - I've highlighted the box you need to fill in.
After you've filled in your location, don't forget to click on the submit button otherwise your changes won't be saved.
You can also add your website address etc while you're there if you want to.