Ensure you are using an FTP Client, such as SmartFTP or CuteFTP and are not visiting this page in your browser. Using an ftp client you would enter the host (webhost.dynadot.com) and your username/password given to you when you signed up for webhosting.
i have my username and password the problem is when i go on ftp://webhost.dynadot.com it doesnt give me the window for to enter them it say the error that i told you
Your error message shows that you are connected to the ftp server.
However it looks like the username/password may not be correct. Please sign into your account and click "edit website" to get your ftp username/password.