url not supported

I am a brand new user of smartftp who has not got to first base.

When I try to upload the index file to the website, where it asks for the address of the host server, I first I put in my website name, but nothing happened except "error Url not supported".

Then I thought it should be the address of the HOST SERVER gatorhost. After putting in http://www.gatorhost.com, it still came up with error message URL not supported.

What does this mean? How can I correct this error?

Does this mean that I have to buy the software and then the urls will be supported? If so, it doesn't give me a 30 day trial to see if I like the software.

Please help me. I am so keen to see my website up for the first time.