On the shooting menu scroll down until you select the "Intvl Timer Shooting" option. Press Enter or hit the right button.
"Start" lets you select when you want the sequence to start. "Now" will start the sequence as soon as you finish setting up. "Time" will let you set a time. Move up or down to choose.
Now you have to hit right to move to the next option.
"Interval", this lets you select the delay in Hours, Minutes and Seconds. Press up or down to change the numbers and right/left to move between the boxes.
You must have some delay selected in the interval (what would be the point otherwise?).
Hitting right will scroll you down to the next option - "No of shots".
Number of shots has two parts. The first is the number of sequences the second is the number of frames per sequence.
OK so you are probably wondering why on earth you might want to take more than one shot per interval? Well the reason is that during the duration of the shoot the lighting might change. If you set the camera to a bracket mode eg. 5 frames of 1 stop apart, you can select the same number of frames per interval then you are virtually guaranteed to get some kind of image for every interval that will be close enough to the right exposure no matter how badly the light changes. Easy.
OK, nearly home.
Now there is the "Start" option with two settings, "Off" or "On". This is not the same as the "Start" time from above, this is how you trigger the interval to start shooting. You move the cursor over the "ON" selection by hitting the down button then hit enter to select it.
The camera will now wait for the first interval or the correct start time. You do not need to hit the shutter button, the camera will take over until it is finished.
Leave the camera on autofocus and it will refocus for every sequence if something has moved. Leave the metering on P, A or S and the exposure will also be adjusted.
It's also a good idea to slide the rear veiwfinder curtain down to prevent any stray light entering the metering system from behind the camera while you eye is away from the veiwfinder.
That's it, no need for a remote shutter cable or seperate intervalometer, it's all built in. Hope that helped.