When I am trying to accept an answer for my question, I am asked to wait for 2 minutes. Why is this? I am trying to accept it soon after I got the answer from him -- within a minute. Is there a rule about this?
This is to allow others to post better answers, and for the community to give input on the answer via voting.
Point is, once a question has an accepted answer, fewer people visit it. The green box gives the impression "nothing to see here, move along".
So, the system makes sure you wait a bit before you accept the answer. There's no hurry, wait a bit :)
Additionally, it reduces the impact of the Fastest Gun in the West Problem