How to calculate response time.

Hello.
I have a task to do which is as follows:
I have to do an "id query" on a primary key of my db and then calculate the response time of the query.
Task says that i'm able to take screenshots of a graphical view of response time.And as a hint says that there are sql commands that can do such thing.Allthough i've searched the books i have access to and the internet i can't find such thing.I dunno maybe someone more familiar with this stuff can understand what i'm supposed to do.I don't want to give me the whole solution but just if u can tell me where to look.
I don't understand what means "do an id query on primary key 'SMTH' " and i can't find anythin which is related on calculating system response time to execute a query.
Any help is much appreciated.
Thx a lot :)See set statistics statement, set statistics time in particular