My parents have my computer and I'm going to yell at them to give it back.
In order to get your computer back do you have to yell at them?
I'm angry and I need to vent.
You shouldn't yell at your parents. They probably have a valid reason for taking your computer and yelling at them is only going to make the situation worse.
Tell me about it. They won't let me have my computer till I can get good grades.
It seems you understand why they took it, but yelling at them would be wrong. Perhaps talk to them calmly and explain that at least having some access to your computer will help you with school work and improving your grades.