When I see a posting like this it's difficult to tell if it's from a student trying to complete a class assignment, a hobbyist trying to develop something, or a professional with a project that's over their head. From the info you've given, I'd assume it's one of the former two.
In any case, your requirements are severely lacking in detail, and I have to wonder as to why you choose some of the technologies you did (PIC processor, USB interface). In any case, I won't tell you how to solve your problem; at least not for free, as that's how I make my living. But I will give you some direction and hopefully make you think about possible solutions.
First of all, connecting a USB camera to a microprocessor is a relatively difficult task. You need a uP with that acts as a USB master and you need to write a significant amount of code just to handle the USB interface. A better choice would be a camera with a I2C, or SPI interface. Most uP's have one, or both, of these interfaces built in, and there's relatively little code required for the interface driver. I'd suggest you look at
www.Sparkfun.com - they typically offer a couple of differant low-cost cameras with these types of interface. There are also many other suppliers available.
You may want to consider getting a camera with a built-in JPEG encoder. I beleive that SparkFun used to sell these, I don't know if they still do. However, they are readily available. This would eliminate the need for you to handle the compression on the processor.
Lastly, you don't indicate how you intend to send the image to the cellphone - you indicate you cant use 'the net' - which I assume means the Internet. So how do you intend to send the image? GSM?
Hope this info helps you.