Orange trees are native to the warm climates of China, but are now grown throughout much of the world. Like other fruit grown on trees, they start out as flowers that must be successfully pollinated to produce fruit. The main reason an orange tree does not produce fruit is because the flowers are not pollinating. You can help promote pollination without special tools or experience with this type of work.
Wait for the flowers on the tree to bloom. This typically takes place in early to mid-spring.
Set up a ladder if the branches of the tree are too high to reach from the ground. If necessary, bury the legs of the ladder in an inch of soil to help secure it in place.
Tap the end of a branch with your finger to make the branch and flowers bounce up and down. This will cause the pollen to dislodge from the flowers and fall to the pistil.
Repeat the process for each additional branch. The process can be time consuming, but the work is easy as only a slight bump is required to promote pollination.