if you have a BIS/BES account, you can download directly over the air (OTA) via the supplied link. If you do not have a BIS/BES plan you need to email the creator for the .jad/.jar files.
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If I'm not mistaken there is a theme section on this forum for each different model. There will be OTA links and all you gotta do is click the link and voila! Just download and your set it will usually ask if you want to switch your current theme with the one you just downloaded so just press okay
*curve 8900 and tour themes work on the onyx as well
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