Should you let your brother use the computer?

What??

No, he should 'go' in the toilet.

I am struggling to understand your question. Do you mean, "Should your brother log in to your laptop computer"? If that is the question, then the answer is, "If it is really yourlaptop, then it is up to you to decide". If it is actually your parents laptop that they let you use, then it is up to them to decide.