Generally we set up 376+954 with the ones, tens and hundreds columns lined up vertically:
Now we add the digits in the ones column.
This results in 10 and so we place 0 under the line in the ones column and carry the 1 into the tens column.
Now we add the digits in the tens column.
This results in 13 and so we place 3 under the line in the tens column and carry the 1 into the hundreds column.
Now we add the digits in the hundreds column.
This is 13 so we place 13 under the line so that its rightmost digit is in the hundreds column.
The answer is therefore 1330.