How do you reply to someone who wrote to you?

First of all, I would like to reply to Knucklesmac and explain that since I wrote and asked the question, I learned that this item I have is a battery for a modem we used to have in the past. Thank you though for your help. We are online and have a modem that is connected to our computer and that enables us to go online. It is through Western Broadband. We have this modem connected to our iMac and it works fine. When I received your reply, I wanted to answer you but couldn't figure out how to do it. Years ago, I went online all the time to the Apple discussion group and talked about things but it seems the web site has really changed and I can't figure out how it works and then on top of that, none of my passwords worked and I had to keep creating a new one. When I go to discussion, my email address appears in a box but it isn't the same as what I thought my user name was that I created. I must be getting too old to do this. Usually I am pretty good at figuring out things on the computer but this web site has really thrown me for a loop. Thank you for all who have writtten to me and helped. Noel