FreePBX and Asterisk Configuration

Hi i have an installed version of Trixbox CE which includes Asterisk and FreePBX Some troubleshooting is needed as i can make outgoing calls fine but i cannot receive incoming calls from the same voip provider/trunk It is something very simple but i am unaware of conf files therefore just cant get it to work. If somebody can configure this for me remotely and get my PBX all up and running that would be brilliant. As soon as the PBX can receive an incoming call onto the the IVR Menu and then when user selects option onto the specified extension i will consider this project a success and release payment. Also if you could note step by step instructions of what you did if i have to clean install again that would be great. Thanks