For this tutorial, you will need to select the text tool. You will see a bar that says KEARNING, and LEADING.

Kearning is for how close each letter will be, and leading is how far apart from the end the sentences will be. Examples:

Kearning
Kearning causes your letters to become closer together. This is kearning when its set to -209 and the font is arial size 36.

Leading
Leading causes spaces between sentences underneath each other. This is leading BEFORE you change the settings:

Here is the result after I set the leading to -400:

I hope you now get the concept of kearning and leading. Making the numbers negative will cause the text to be smushed and closer, while adding a positive will give it more space.