I am not sure what you mean by placing the first digit, but I am going to assume you need help with this division problem.
We are dividing 315 by 9
First figure out how many times 9 goes into 31.
3 times right?
Now do 9 * 3
9 * 3 = 27
Subtract 27 from 31
31-27= 4
Now how many times does 9 go into 45?
5 times
Putting the 3 and the 5 together, we can conclude that the answer is 35