Often your camera will come with some imaging software, and this should help you. Alternatively you can simply plug in the usb download lead that came with the camera, and when you switch the camera on your computer will recognise it as a storage device.
You can then navigate to the image ou want, right-click on it and choose 'open with ....microsoft office picture manager', a simple program that has an 'edit' and 'save picture as' option - choose jpg or gif from the latter.