The four seals are:
1) To the left of the third town, there should be a forest dungeon. Go through it and continue onto the tower on the island. That's one of them.
2) If you go all the way down from the third town, then all the way left, you should eventually find a oasis in a forest. That's another.
3) To open up the third one, go all the way left from the third town to a fourth town. There, go up to the castle and view the scene on the second floor. Afterwards, go back to the third town and go down past the desert to another town. In there, you should see a blond guy in a cape. Talk to him, and he'll open up a hole in the swamp on the very southeast of the continent. That's the third one.
4) For number four, when you're in the castle town, go to the tavern and talk to the guys inside. One of them should show you a castle in a forest. Go back to the first continent and go all the way down from the second town. That's the fourth.
Incidentally, for anyone who hasn't gotten to that point yet, if you talk to the mayor of the desert town while not horny, he'll give you a quest to beat up the bandits in the desert. Once you do so, he'll give you the Holy Water of the Saint. There's a guy in the bar of the third town who wants you to go to the orc den south of the third town, above the bandit hideout. Once you beat the orc boss, you can retrieve the Holy Sword with the Holy Water. With the Holy Sword, you can kill the barriers protecting the bosses of the seals.
