As all said, it's not worth it. I mined there one year ago for about a month for ~2300 satoshi, which is too small to be withdrawn.
However, nobody answered your question.
1. go to
https://mining.bitcoin.cz/accounts/profile/workers/ and create a worker. For example: yourWk
2. go to
https://mining.bitcoin.cz/user-manual/getting_started and look how the command line should look like.
You should have:
host: stratum+tcp://stratum.bitcoin.cz
port: 3333
worker name: yourUser.yourWk
The password is not the account password, it's the worker password. If you didn't have to create password for worker, you will put anything you want here, for example: x
I write this because it may help you on other pools / other mining programs / other coins.