Can't log in

[12:56:59] SmartFTP v2.0.996.33
[12:56:59] Resolving host name
12:56:59] Unable to resolve host name.
[12:56:59] Active Help:
[12:56:59] Cannot login waiting to retry (30s)...

This is the message I keep getting, I have tried to re log in with my host name but it will not recognise me
any idea how I can fix it please. I am very very new so please explain in very easy terms.