Use a garden shovel to dig a hole in the dirt deep enough to cover the root and bottom of the plant. Remove the azalea from its container and loosen the roots. If it is pot-bound (roots tightly circling and too close together) you may need to cut some roots in order to do this. Dig a few inches wider than the ball of the root, and set the azalea upright in the hole so that the top of the root ball is slightly above the surface of the ground. Drop soil into the hole around the plant. Spread it around and under the azalea, and lightly pat it into place with your fingertips.  Wet the azalea before planting. Dip the root ball in a bucket of water, or use a hose to lightly dampen it, before setting the azalea into the ground.  If you are planting more than one azalea, make sure the holes are space several feet apart. Water the plant and the soil slowly and thoroughly. Water again the day after planting. The plants must be watered at least once per week, unless they are in direct sunlight, in which case they must be watered more frequently. Take care not to let the azalea dry out, or it will wither. Use pine bark, pine needles, sawdust or wood chips between the bushes. This will keep the soil moist and the temperature of the dirt even. Mulch will also help keep out weeds. A good time to re-apply mulch might be after the blooms have faded. If your soil is rich and acid, there is probably no need to fertilize and generally azaleas grow quite well without extra nutrients. In fact, over-fertilizing is often worse than not fertilizing at all since their shallow root systems can be damaged by fertilizer. If you do need to fertilize, do it in spring, right after the azalea blooms. Use an acid forming fertilizer like cottonseed meal, or choose a special azalea fertilizer. Improper fertilizing can also cause the plant to bloom at the wrong time, so be sure to fertilize only if required.

TL;DR in Vietnamese:
Đào một hốc đất và trồng cây. Tưới cây. Che phủ kỹ cho cây đỗ quyên. Chỉ bón phân cho cây đỗ quyên khi cần thiết.