To show numbers as currency, you can apply either the Currency format or the Accounting format.
Select the cells that you want to format and then, in the Number group on the Home tab, click the down arrow in the Number Format box.

Choose either Currency or Accounting.
Currency

With this format:

The decimal points appear aligned in the column.

The currency symbol appears next to the first digit in the cell. (That is, it is not aligned with the other currency symbols in the column.

I hope this helps!
Tim Paine