how do i set up auto numbering columns

i am a former excel user and i used to do this certain command, but now that i use mac i dont know how to set up autonumbering automatically in a column....

for example

1

2

3

4

5

...... so on and so on, but my numbers start like in 31311, 31312, so on and so on...

please help.

thanks...

"Sending out an S.O.S."....

Sting.

"message in a bottle"