You need 2 conditional format rules. Both applied to cells B2:B, with Custom formula is selected. In the first, set the formula to:

=B1<B2

and set the color to the Red you want to see. In the second, change the formula to

=B1>B2

and select the green color you wish.

UPDATE FROM COMMENTS:

You need 3 custom format settings, all applide to the range B3:B. The First is set to

Format cells if...     Cell is empty
and the fill is set to None

The second and third are Custom Formula where the Formula are:

For red:

=B4<B3

and for green:

=B4>B3

OLD INFO FOR Comments

You need 2 conditional format rules. Both applied to cells B2:B, with Custom formula is selected. In the first, set the formula to:

=B1<B2

and set the color to the Red you want to see. In the second, change the formula to

=B1>B2

and select the green color you wish.

You need 2 conditional format rules. Both applied to cells B2:B, with Custom formula is selected. In the first, set the formula to:

=B1<B2

and set the color to the Red you want to see. In the second, change the formula to

=B1>B2

and select the green color you wish.

You need 2 conditional format rules. Both applied to cells B2:B, with Custom formula is selected. In the first, set the formula to:

=B1<B2

and set the color to the Red you want to see. In the second, change the formula to

=B1>B2

and select the green color you wish.