Yes, I agree that you should probably learn more about Codeigniter first. Your question is really a database question, not really related to Codeigniter. Are you also new to databases? You would need at least two table, one for your users and the other for your posts. Then you would join the two tables. You only want one post from every user, the very last post they made? In that case, your query would probably use the MAX() function to find the post with the highest date value for each user.
Hey, don't work without a PHP debugger. Several free IDEs have this features built in. Two are NetBeans and CodeLobster. Without a debugger, it's like you're driving with a blindfold on -- you are going to crash!
