Apple has made iPhone very restricted in terms of customization, but there are ways to bypass these restrictions and install custom themes, "iPhone Hack Toolkit" is a free iPhone jail-breaking software.
- Download iPhone Hack Toolkit Ver1.0 (Download Link at end of the post)
- Connect your iPhone with PC (Ensure you have installed iTunes software on your PC).
- Open iPhone Hack Toolkit Ver1.0 software.
- First “Jailbreak” your iPhone, choose “Import” and insert .pkg file (download it from here).
Now enjoy your new iPhone theme :)