Or you may want to have the entire picture in focus to see all the beauty...
This is very easy to do, if you know what you're doing. DOF is determined by what f-stop (or aperture) you use. Think of it like your eyes. When you squint, you can see more focused than when they are wide open. The same goes for your camera. The smaller the opening of the lens, the more in focus you will see. Now, the numbers of the f-stops are a little tricky. You would think that the higher the number, the bigger the opening, right? But those numbers are actually fractions - all with a 1 over them. So a 5.6 f-stop is actually 1/5.6 open and a 22 f-stop is actually 1/22 opening. Basically, what you have to remember is that the lower the number, the less you will have in focus. Also, the more you zoom in, the less you will have in focus as well.
For you beginners out there, grab your cameras and play along with me. First, you have to have your camera set on the manual setting. (Usually this is marked with an M on the dial - if not, check your owners manual to see how to set it to manual.) When you go up on your f-stop, you must come down on your shutter speed and vice versa, otherwise you will not have the right lighting. You can change your ISO speed as well. Remember that when you change your f-stop, you are changing the opening of the lens - in other words, you are letting more (or less) light into your camera. I suggest you play around with it until you get the hang of it. Just play with your camera and its settings. Don't be afraid of it.
I took these shots this morning. I did not edit them in any way just so you could see the difference between them. This one was shot at ISO 100, shutter speed 100, f-stop 5.6. See how the leaf is in focus and it gradually gets more out of focus the farther you look from the leaf?
This one was at ISO 1600 (I went so high just to be able to show the most difference I could get between the two shots), shutter speed 125, f-stop 25. See how mostly everything is in focus even though I still focused on the leaf?
Now go play! And I'll see you tomorrow for my Perceptive Perspective when its Depth of Field and you can show me what you've come up with!