The period is given by - you are given that
"Maximum Value" is a synonym of amplitude which is A in your equation
Now you know A you can find C by subbing in (0,6) for (x,y)
The maximum value of y= A sin(Bx+ C) is A.
If for some x, Bx+ C= 0, the when (subtract the first equation from the second) . Since we are told that the period is , we can take to get .
Finally, the maximum occurs at . Since we are told that it happens when x= 0, we must have .