How can you make a piece of land into your country?

What you would need to do is declare independence and be prepared to fight against the government that currently controls the area where your land is located. Then be prepared to defend your tiny nation from other nearby countries that may try to grab your land. Petition the United Nations and the G-20 and NATO for recognition. Doing all these things, you now have your own country. Whoever's asking, good luck with that.