How to go about selling my camera?

I have a Nikon touchscreen red standard point-and-shoot camera (the one from the Ashton Kutcher Nikon commercial).It has terrible image quality and I hate it. I'm going on vacation to California in 2 weeks and I want to be able to take good pictures. I want to sell my camera and upgrade to a Nikon D3000. How should I sell my camera? I want to get the money for it as quick as possible (within 2 weeks). The camera costed about $400 and the Nikon D3000 costs $400.

Ebay, sell it to second hand shops, ask around…

Ebay. You'll get the money as soon as someone buys it.
If you don't want to do it online, you could try going on kijiji or craigslist, although it might be harder to sell. People on those sites will try to barter with you.

Sell it for $200, I'm sure someone will buy it, post it in Facebook, Twitter, etc. ; so the people in your friend list can see it.

If Kutcher uses it, it shouldn't go wrong!

You're just failing to give the camera enough light. Set it to Auto mode, Auto ISO, Auto white balance and 0 (zero) EV. Take shots under the sun. Indoors, use the flash. Step back when too bright, go nearer when too dark. It's all in the light.

There's no sense buying a dSLR if you can't handle a simple point-and-shoot. You will get the same quality of pictures after spending a load of cash. Learn first how to give enough light to your little camera and then you will want to know more. That would be the right time to get a dSLR.

If you don't like your camera, what makes you think anyone else would? And you won't be able to learn to use a D3000 in just a matter of days. Nikons are good cameras. Maybe you should work harder to learn to take better pictures with the one you already have.