Well you shouldn't. If you spend much time in the woods sooner or later you will need to relieve yourself.
As awkward as it might be to discuss such matters, running into a fellow trekker's "leavings" on the trail the other day proved to me at least that some forest walkers still don't know how to deal with their droppings. Sorry Fellas (and Gals!) but stepping off the trail to make stinky is just not good enough. I know for sure that such incidents are committed by second class hikers, no self respecting (or nature respecting) hiker would leave such a mess. So lets take a quick look at what all first class hikers already know.
First and foremost all trekkers should carry sanitation gear. That's really just three items that can be toted in any small pocket of the day pack. A Trowel to excavate a small "cat" hole. These depressions in the earth need not be large, just big enough to receive the contents and be properly covered. The hole should be about ten inches deep and six inches wide (unless you're a really good shot). Any shallower will invite animals to dig up the contents and any deeper will place the contents below the magic layer. The magic layer is those few inches of top soil that contain the highest concentrations of microbial and bacterial life that will brake down the fecal matter.
Secondly, you will need Toilet paper and the type sold in outdoor equipment stores is best. This thin yet sturdy paper is intentionally designed and formulated to brake down with exposure to water and soil. If you choose not to buy this type of paper the standard paper can be used however, try not to use paper with perfumes or dyes. Some scents may attract critters and some dyes work against the natural biodegradable properties of the paper. Cheap paper is best!
Thirdly a few packs of Hand sanitizer or a small squirt bottle of any alcohol based anti bacterial hand cleanser should be carried. The high alcohol content of these towelettes enable you to drop them into the hole and Carefully set them on fire with a match, this will also set the soiled paper on fire burning most everything into ashes. Thus nothing is left to make the wilderness untidy. Ensure the items are out and no subterranean twigs, roots are burning. Cover the contents with the dirt you removed from the hole and camouflage the site with leaf litter and duff from the forest floor.
Now as the Realtor said, the three most important things are Location, Location and Location.
Always conduct such business in a private area where you will not spoil the view should someone come striding up the trail just as you are taking the dive. Stay well away from all water sources as well as camp or cooking areas.
If you have done your job the casual hiker should be able to pass by the deposit without detecting it.
Now as to technique, do what ever you must to get the job done but at risk of revealing my most private moments, I'll tell you how I do it. Generally, I try to find an appropriate spot near a tree. The tree will provide privacy and back support and the Tannic acid or "Tannin" that most trees lose from it's bark as it rains helps brake down the deposit. Dig your hole about one foot from the base of the tree. Don't relocate the soil any further then necessary from the hole. Remove any bulky clothes such as coats and jackets. Stand facing away from the tree with your feet just ahead and on either side of the hole. Lower your pants to the knee and no further. By spreading your knees you will hold up your pants and make a little shelf for your toilet paper to rest on. Now bend and lean back as if sitting on an imaginary chair with just your back against the tree to support you. Here comes the easy part. Empty your bowls into the hole. if you've done everything right, ground zero should be just under you. Clean up as necessary and drop paper into the hole below you. When you are done stand (without dropping your pants) and sanitize the site as above.
I don't know about you but the wilderness is the place we retreat to to escape daily stress and the crap we have to deal with in the "civilized" world.
Lets not deal with other peoples crap out here too.