Hello Charles ; nice to meet you, thank you for accepting my invite, sorry for late response.
If you want to respond to someone that made a comment on your wall, just click on that persons picture and it will take you to their page. Then scroll down to their wall write something and then click submit and you are done. There is alot of information and things to do here, like joining groups, discussion boards, making friends, plus so much more. If you have any questions just leave a comment on my wall or any of your friends comment wall and we will help you.