Tradução - Espanhol-Inglês - Gracias por ofrecer tu colaboración a...

Yo escribí este mismo texto en inglés, sin embargo, me gustaría que lo corrigieran:
"Thanks for offer your collaboration to justfreebooks. I have accepted
your offer with great pleasure and from now you are a contributor. That means that you can add and exclude web sites, or annotate them with any of the current refinement labels.
¿Rules? Just one. Please, avoid to include websites that clearly violate copyrights. In Justfreebooks are welcome those sites that contain public domain books or books whose authors have authorized its free distribution (through a Creative Commons license, a GNU Free Documentation License or another way).
If you find in the search results a webpage or a website that violate sistematically copyrights, please exclude it.
Now you can begin to collaborate!"

Algunos tips extra: Este mensaje va a ser enviado a todas las personas que ofrezcan colaborar en el buscador Jusfreebooks.
El nombre Justfreebooks no debe ser traducido. Si tienen dudas acerca de la palabra "refinamiento" vayan a http://www.google.com/coop/docs/cse/refinements.html

I edited the requester's own English translation, as requested.

[... and I edited yours. -- kafetzou]