It's so exhausting figuring all of this out. I know though once we do the rest of our time here will be so much fun!
Be careful though! Unless you haven't obtained a such one, from the 1st of January 2010 magnetic passes (Warszawska Karta Miejska) have to be personalised with your photo put onto it (I haven't re-changed my old one yet, so no advise from me until then).
For this 90 day bus pass, how do I validate it?
You may buy a pass which is either un-validated (then you can wait with the validation until the time you want to use your pass) or have it validated at the purchase (they often ask you if you want them to validate it for you). If you are re-loading your old pass within its present period of validity for the same-time next period, it's validated automatically (the validation is being prolonged for this next period). If later, you again must have it validated or validate it for yourself. It's always good to check by holding the pass onto the ticket machine (reader) as the reader reads a pass or validates an un-validated one
It's important to validate
your pass or have it validated at the purchase! Once I re-loaded my 30-day pass, but forgot to validate it. I was using it all the month thinking I was OK. I wasn't, and if a controller had come to check, I would have had to pay a fine as my pass was not valid. When I went to re-load it for a next period, the assistant at the post-office was unable to do it since it was charged and not activated (validated). I bought a new pass as they couldn't explain why the machine cannot re-load my pass!!!