Core FTP

i dont understand how to get it so i can view the files. do i type in the ip adress or what?

I have set it up as best as i could but i get a message box saying that the sever name or address could not be resolved so i click ok and it shows it blank with no files. What did i do wrong? is the domain name suposed to be one in use by me or can i make one up with out having to pay? what sould th...