Life / Activation of purchased Poland Orange/T-mobile/Play mobile data / SIM card? [19]

So I just moved to Poland and today I got a polish telephone number (Orange) which included 1 GB data. I also bought an additional 6 GB of data at a newspaper stand and got a receipt with a couple of codes and a whole lot of polish on it.

How do I add these 6 GB's to my SIM-card?

Oh, and also, if I re-charge with my 6GB, will they add upon whatever data I have left or will it just set my total amount to 6GB?