are these addons are like system file and stuff like this? if yes, anyone know a site which i can download them ?
The band tones that you have all free online are files that you download using the interface on GB. They are not all that great and theres not many out but some are fair.

If you go to MF and buy something like the Gold or Silver plug-in pack which range from 100 - $150 then you will get a CD in the mail and install the software your your PC in the directory where GB is installed.

any free downloads for the silver or gold pack is against the law and we here at UG dont help members with that type of work.