Lay out your fence line. Use a compass or transom to plot a straight line across the area you want to fence. Pound stakes at the corners and tie string between the stakes. Following this string line helps you keep your fence straight. Determine where you want to put gates and mark these spaces with stakes also.
Cut the trees you'll use for your fence. Choose straight pine, poplar or other small, straight trees 4 to 8 inches in diameter and 10 feet tall or taller. Cut the trees with a chain saw and remove all limbs.
Choose two 6- to 8-inch diameter sections of tree, each 5 to 6 feet long, for each upright "X." Cut notches the width of each tree approximately 18 inches from the top of each post. Fit the trees together, notch to notch, to form an "X" with long legs. Hammer in a 50-penny nail to hold the posts together. You may wish to construct all these support sections before you move on to working with the rails.
Cut rails 10 to 12 feet long. Any longer and you need some kind of center support posts. Your fence may have three to four rails, as you choose.
Stand one set of support posts upright, the "X" centered on your fence line. Set the end of one rail in the cradle formed by the top of the "X." Attach the rail with a 50-penny nail. Move to the other end of the rail. Stand up a second set of support posts and fit the end of the rail into the cradle of the "X" of the second rail. Secure with another nail.
Attach your other rails to either the inside or the outside leg of each "X." Either place all rails on the inside leg or all rails on the outside leg; it doesn't matter, but they should all be the same. Space the rails evenly, using three or four rails, and attach with nails.
Continuing adding fence sections. At the corners install one set of supports perpendicular to another and begin a second line of fencing at right angles to the first.
Skip over spaces you've marked for gates and continue your fence on the other side. For gates, dig holes for gate posts and set the posts in concrete. Attach the gate to these posts. For a temporary gate, slide rails between two sets of X supports. Allow the ends of the rails to overlap the rails that are attached to these supports and rest on top of the attached rails. To open the gate, slide the rails over enough to allow you to pass through.