You have learned to conjugate the subjunctive. Now you are going to learn the most basic usage: when you want someone else to do something.
If you want to eat tacos, you would say, "quiero comer tacos". But if you wanted your friend to eat a taco you would say, "quiero que comas un taco". Literally you would be saying, "I want that you eat a taco".
Try this activity that will teach you the word order of a subjunctive sentence: (1) Put the parts of the sentence in order
Now do this 10 question activity that will help you identify when to use the subjunctive:
(2) You want someone to do something
Note that not all answers require the subjunctive. Think: is it saying that someone wants someone else to do something? Press refresh and retake the quiz until you get 90% correct (the quiz is different every time)
(3) ¿Qué quieren los estudiantes?
Do the above activity until you have placed all of the verbs in the correct place.