HOw do I use enter to return to the first cell in the next row?

I'm entering data into columns, left to right. When finished with the cell in
the last column(H), how do I get to the first cell in the first column(A),
next row down? Just like entering text in Word and using the Enter key as a
carriage return to start the next line.
The only way it works now is to use the left arrow key. If I hit return I
simply drop down to the next lower cell in same columm.