I'm not an english or german native speaker, so I hope I can explain this:
zahlen and bezahlen both mean to pay. There is no real difference, I think the general rule is zahlen is used as in "to pay money" and bezahlen as in "to pay for something".
gezahlt is the past perfect of zahlen:
I pay - Ich zahle
I paid/I have paid - Ich habe gezahlt
Because german has so many conjugations (i pay - ich zahle, you pay - du zahlst, we pay - wir zahlen) you can find a lot of them still available, even more so as .com since germans prefer .de.