I have never done dumbbells or any type of strength training, So how much should my dumbbells weigh? I am 15 years old

I don't have time to go to a Gym so I workout at home. I have Dumbbells at home. What are some effictive excerises for my tricepts using dumbbells?

I'm looking to improve my arms, such as tricepts,bicepts,shoulders, and maybe chest region. Using only dumbbells, does anybody have a good and effective routine that can be done in about an hour a day or less? Thanks!

Ok I have dumbbells here so what are good ways to excerise with dumbbells so I can become stronger and my arms can get a little bit bigger?