Back when you were a kid, your parents always told you and your brother the family legend about your grandfather's hidden treasure. It was quite a good story, and there was even an ancient map and a letter to support that the crazy man really did hide all of his money somewhere in your area:
Now that your parents and brother are long gone, your house is on the brink of collapse, and you work almost fifteen hours on the field yet can't earn enough money to pay back your debts to the merchants of the eastern trading post, this hidden treasure is the last hope to get your life together.
The letter in plain text
To find my treasure you have to leave our house:
Though it is the center of your map, no one finds adventure who stays in his bed.
The riches do not wait for you at the cliffs of the volcano of despair
In fact, the opposite of fire will show you the way.
But don’t rush! I did not say you should go to the watery marshes, my fortune is not there.
The best you can do in the swamps of sorrows is that you place the eastern trading post to
your north... then don’t go there, no, quite the opposite!
Maybe the place is the fields of labour - will you find money through honest work?
No, I’m kidding, just find my hidden treasures, which are nowhere near that place.
The only tag on this puzzle is visual, so it needs to be approached like one. The raw text of the letter won't help you by itself; there is a reason why it was posted as a picture originally.
The map and the letter are on two different papers, and the size of the images reflect the scaling of these papers. Basically, they have the same width.
As with every good treasure map, there is a clearly visible X on this one too.
Additional useful information, thanks to Weather Vane's work:
Weather Vane inspected the map very carefully, but couldn't find any hidden information in the colors or the font choice. (There is no steganography.) This is only a regular map on an old paper. It has a thick paint layer on the colorful parts, which do not hide any secret, and the white places were most likely scrubbed to make the paper more transparent and give it a more visible distinction.
Skylar's work showed us the following:
Skylar found one of the three important instructions in the text:
"place the eastern trading post to your north" which makes him think that a rotation takes place somewhere in the puzzle. Correctly finding all three hints will tell you exactly what to do with the map to find the treasure.