Configuring a dialup connection

[eddie57 at peoplepc.com]

I just recently installed ubuntu 5.10 and the installation went just 
fine except that when i try to setup a dialup connection it keeps 
saying  modem not detected even though the modem is listed in the device 
manager window. So the modem apparently was detected during 
installation. I tried executing the pppconfig command from a terminal 
window. I got the message "must be logged in as root" so i issued the su 
command. It asked for the root  password which i gave, but got the 
message authentication failure, so i issued the su command followed by 
my user name. It asked for my password again which worked. I tried the 
pppconfig command again but it said bad command. Any help would be 
appreciated as i would like to spend as little time as possible in windows