[RCU] Roundcube Not working

Hi,

I just downloaded and installed Round cube, but I can not get it to work. This looks like it may be a good component, if I can get it to work. I guess my biggest problem is I don't understand the configuration very well. I know what my smtp server is. Both for outgoing and incoming. And my servers port is 80 Ya;ll have the default for 25. I have tried different things and can't get it to work. I don't understand the managing users either. What is suppose to go in the "Mail Host" and "Alias" fields ? I need help in configuring this component please.