I recommend this webiste from the National Park Service for getting information:
http://www.nps.gov/grca/index.htmThere are many ways to explore the canyon, depending on the season and your skill level. You can take a hiking trip that can last a couple of days, but hiking can be dangerous in the summer months because it can get extremely hot. In the winter, there is actually snow as well. For tourists wishing to see the canyon in other ways, there are a number of options. There are several hotels/lodges and you can also drive your car to the different lookout points.
There are also different ways of getting into the park - North Rim and South Rim, so you would get into the park differently depending on where you're coming from.
The best, most colorful pictures come out either during sunrise or sunset.