After clearing Parapa Palace, go back to the cave that you went through to reach the desert. Now it is brightly lit, allowing you to see the Lowder that was invisible before.
When you're back outside, head southwest, past Rauru Town and the forest, and go to the area southwest of the North Palace. There is a cave here with Lowders and Red Octoroks. The Octoroks jump and spit a rock, so be sure to block it with your shield. At the back of this cave there is a magic container. It adds another block to your magic meter.
Now go outside and head northeast to return to the dirt path. Take the path that goes northwest. When you see the desert above this path, and you are just before the forest on the west, go north into the desert. This is the Tantari Desert.
Go north to reach a cave. Go inside.
There is a blue Ache here. It looks like a bat, and when you get close to it, it swoops down, either toward you or away from you, and then flies back up to the ceiling. To defeat it, just hit it when it flies down.
Carefully jump over the lava while avoiding the rocks from the Octoroks. After you get rid of the second Octorok, you will soon find a red Goriya throwing boomerangs at you. You can try to jump over the boomerangs or block them with your shield. Remember to watch to see where the Goriya holds the boomerang before he throws it. And remember to avoid the boomerangs when they start going back toward the Goriya.
Eventually the Goriya will be gone, and you can get the trophy that was behind it. Now you can exit the cave and go to Ruto Town.
To get to Ruto Town, head south from Tantari Desert until you're back on the dirt path. From there, you just need to follow the path going northwest. You will reach Ruto Town soon.
In town, you will find another of those women in red dresses who walks around in front of her house and will heal you if you talk to her and follow her into the house. There is also an orange old lady outside of a different house. This is the magic-refilling lady. Talk to her and follow her inside to get your magic refilled. You will find the magic-refilling lady in all of the towns except for Rauru. In this first screen of Ruto Town, you can also find Error's house. As you might know, his three-word dialog, "I am Error," is famous.
At any rate, in the second screen of Ruto Town, you will find another woman in a red dress, but she isn't a healer this time. She's the owner (or at least the guardian) of the trophy that you obtained from the cave in Tantari Desert. (If you didn't get the trophy, she will tell you that it was stolen, so go to the Tantari Desert north of the North Palace and into the cave, and get the trophy from there.)Now that you have the trophy, she will let you into the house. Follow her, and then go to the basement where the old man will give you Jump magic. When you cast Jump magic, you can jump higher. Don't forget that the magic wears off as soon as you go to a different screen, though.
You can explore the town more if you want, but at this point you have seen all of the important parts, so you can leave, although be sure to refill your magic if it isn't maxed out right now.
Your next destination is Saria Town.