Can someone please help me???

Before I post something else interesting, I would like to know about Xanga etiquette. When someone posts a comment responding to one of my posts, how do I respond to that? Do I post a comment under their post on my blog? If I do that, do people go back to see what I have replied? Or, do I post a comment under one of their blogs? Please help!!! I don't want to be rude, but would really love to reply to people's comments on my blog, I just don't know what is customary. Thanks everyone!!!