Now trust me i don't know how to make a report in yahoo and am so sorry abut that , i wish sombody will help m?

the man he left his name is Umaru han and his number is0022678257834 and he is saying i do advice you to keep this as a top secret!!! i wish i know how to do a report in yahoo,why i want to make a report maybe this man he want to do something bad in uk, so that is why i am so worry