Its the same as excel; Either right click or click on the small arrow on the letter (where you want to open a new column), from the new menu select add column (insert 1 left/right that's it, at least i do it that way.

As for 2-3, 1st on the lower stones, than depending how it ends up use the second bird. I try to kill the pig on the left with the 1st bird too, surely need luck..