Consult the manufacturer's recommendations for appropriate installation of any included hardware and follow those instructions, if possible. If you did not get hanging hardware, or it is not useful for hanging the chair from a tree, proceed to the next step.
Choose a healthy tree with a horizontally projecting limb. To support an average adult, pick a limb at least 6 to 8 inches in diameter. You can use a smaller limb to support children or small adults; a larger limb is needed for heavier individuals.
Climb a ladder to get high enough to drill a hole in the projecting tree limb. Enlist a helper to hold the ladder steady while you climb and work.
Measure 3 to 4 feet out along the limb from the trunk of the tree and mark the spot. Insert the spade bit into the cordless drill and drill a hole all the way through the limb from top to bottom at the marked spot. Keeping the swing close to the trunk avoids undue stress on the limb, decreasing the chance that it will break under pressure from the swing and its occupant.
Push the eye bolt into the hole from the bottom so that the threaded end sticks out at least 1 inch above the top of the limb.
Place an appropriately sized stainless steel washer over the end of the eye bolt and attach two matching nuts to hold the eye bolt securely in place.
Tie the swing support rope to a heavy duty stainless steel carabiner and snap it in place on the eye bolt.