Welcome to FT, and no need to apologize for your English, it is fine.

KL's online check-in procedure is fairly straightforward. Just follow the step-by-step instructions. You will be given the option of checking-in additional passengers, just click on the button.

Boarding cards will be issued for each passenger for each segment/flight, you can print them, have them sent to an e-mail address, etc.

At Amsterdam, your luggage will automatically be transferred to your final destination.

Johan