Go to Rito Village to ask the elder about the Divine Beast Vah Medoh.
Go to Rito Village
Float down off of the north wall of the Great Plateau, then go west. If you have not yet tamed and boarded a horse at a stable, tame a wild horse in the hills north of the Great Plateau. Then go west on the path that goes along the north wall of the Great Plateau. At the fork in the road, go northwest to find a stable. Get a horse there if you have boarded one before, or register your horse if you just tamed one.
Then continue going north on the path. You will cross Manhala Bridge, then there will be another fork in the path. Go right at the fork. You should be able to see a couple of towers in the distance. You will pass through one of the locations from the pictures for the Captured Memories quest. Eventually you will cross Jeddo Bridge. When the path splits, go to the left. (You can visit the towers to the right first if you prefer, but you will need protection from the cold, and it will take longer to reach Rito Village if you go that way.)
If you went left at the fork, ride your horse to the stable just before the bridge. You might want to board your horse here, because the area beyond the bridge is a bit dangerous for horses.
Then go across Tabantha Great Bridge. You will see a Guardian Skywatcher on the path ahead. To avoid it, if you are on horseback you can carefully avoid their spotlights, or if you are not on horseback you can climb up the hill just after the bridge. Go northwest on the hill. There is a Great Fairy Fountain on the northwest end of the hill, so you might want to visit it before you continue.
Then go to the hill with the tower on it. You can make your way up the hill, battling Moblins, or you can just stealthily climb up the hill in places where enemies are not patrolling.
At the tower, climb the column west of the tower, then shoot an arrow down at the eyeball on the column north of the tower. This will make the column fall onto the tower. Go up the fallen column and climb to the top of the tower from there.
From the top of the tower, you can see Rito Village to the north. It has a tall rock spire coming up from the middle of it. Use your map to see how to get to the village from the tower.
When you get close to the center of the village, there will be a cut scene showing you the Divine Beast.
Go to the village and make your way up the walkway that spirals up the rock spire. Near the top, you find the Akh Va'quot Shrine. After visiting the shrine, keep going up the spiralling walkway until you reach the house at the top. The elder is there. Talk to him. When he asks, tell him that you have a Sheikah Slate, then listen to his request.
After he tells you to find Teba, go into the house next to the elder's house and talk to the Rito there. She tells you to go to the Flight Range to find Teba. She says that you can get to the Flight Range by floating from Revali's Landing, which is next to her house. You will recall a memory of Revali.
You will need protection from the cold. You can purchase the Snowquill armor set here in Rito Village.
You can float to the Flight Range from Revali's Landing as mentioned above. Then visit the Sha Warvo Shrine.
Afterward, go north to the Flight Range. Go into the building and take the bow and arrows that are sitting inside. Teba is sitting on the landing overlooking the windy area. Go toward him and there will be a cut scene. Talk to him and offer to help.
He asks you to shoot five targets in three minutes. After the countdown, fall off of the landing and use the Paraglider. Then draw your bow. Time will slow down, giving you more time to aim as you fall. Your stamina will deplete while you aim, so don't take too long. Your stamina gets refilled when you use your Paraglider again. Float around shooting targets until Teba calls you back.
Teba says to take the bow from the treasure chest, so take it, then talk to Teba if you are ready to go to the Divine Beast. He will give you 20 Bomb Arrows and tell you to have protection from the cold.
A Duplex Bow is helpful here because it can do double damage, allowing you to kill each cannon with one shot instead of two.
Enter the Divine Beast
If you are ready, Teba will fly you up to the Divine Beast. You need to shoot the cannons at the edges of Medoh's force field. If you need to stop, just float straight up with the Paraglider.
Get as close as possible to each cannon before firing to help ensure that you don't miss the target.
Medoh will try to shoot at you if Teba is not close enough to draw its fire, so be sure to let go of the Paraglider when a cannon shoots. You will fall quickly enough to avoid the laser blast.
After you have killed all four cannons, you can enter the Divine Beast.