You can not connect to Filezilla (As you posted into the Client forum, I assume you mean Filezilla Client).
If you want to connect to Filezilla Server, however, you have to create at least one user. Without users it's not possible to connect.
hostname: IP address of the server computer. Internal IP if you test from the same network, external IP if you test from outside.
username: the user you just created
password: password of this user
for the administration password I put admin because that is the password for my router and I cannot log in
Filezilla products have nothing to do with your router, they will never ever use passwords from it.
I even opened ports 20 and 21 on my computer.
That's not enough, you need to do more. Read Network Configuration
## BEGIN SIGNATURE BLOCK ###
FTP connection problems? Do yourself a favor and read Network Configuration
.All FileZilla products fully support IPv6. http://worldipv6launch.orgAll support requests per PM will be ignored!
### END SIGNATURE BLOCK ###