can't log in

I cannot log in to my site. I use the coeect user/pass. The site is credit-cards-selector.com
In the URL section, do I put ftp.credit-cards-selector.com, credit-cards-selecror.com
Do I have to put a "/" somewhere?

no, that shouldn't be necessary. most likely your login data is wrong. double-check them and mind that passwords are case-sensitive.
BTW: i copied your link and tried to reach that server. your link contains a "http://" prefix. be sure to skip that when you really connect, so just enter "ftp.credit-cards-selector.com" (no prefix, no slashes).

I have tried with 2 of my sites and it sweems not to be working. I am using port 21. Is that correct?

I was able to reach ftp.credit-cards-selector.com through DOS- naturally, I couldn't login to it, but I was able to reach it. Have you tried using DOS yet?

For questions about ports (although 21 is the default FTP port) and connecting to your FTP server, your domain host would be the best place to start. If, later, you can FTP into your domain some other way but not with SmartFTP, then head back here.

Good Luck...