I'm new to Excel, please forgive me if these are silly questions...

1/

I have three columns - the cells in A and B contain numbers
and I want the cells in C to be those in B minus those in A
i.e.

C1 = B1 - A1
C2 = B2 - A2
and so on.

To achieve this, I don't want to have to go down the whole column
typing in box C1 " =B1-A1 " and typing in C2 " =B2-A2 "
and so on.

Is there a way I can apply one function to the whole of column C
to save time typing?

2/

Different problem...

ROW () gives the row number. So if I type in box C6, ROW() it gives the
number 6.
But if I want C6 to contain the contents of B6, why doesn't =B(ROW()) work
i.e. the ROW() is 6 so it's equal to "=B6". What am I doing wrong?

Many thanks for any advice.