Hi doctors, just half an hour ago I picked a tiny hard pimple. Now its red and theres a small hole! Would it close up again? Would toothpaste work?

Bandaid. Put triple antibiotic ointment and bandaid over it. If you have fever or redness spreading and condition changes to the worse see a doctor.
See ur dentist. I presume you mean in your mouth? Sounds like an abscess, and yes it may "close up again", but that does not solve the problem. Please go to your dentist and have the area evaluated, which may include an x-ray to determine the health of adjacent teeth to the area.
It's okay. While picking or popping a pimple can lead to infection, most often it doesn't. The area should heal without any treatment, but you can play safe and apply some hydrogen peroxide available at drug stores and supermarkets. Toothpaste may dry it up; I have many patients who swear by it!