If you want to format the way numbers are displayed you can find an extensive range of options under the 'Home' menu. The default cell format is 'General'. The options include 'currency':
A faster way is to select the cell (or range) and 'right click'. This is a convenient way of accessing various frequently used functions. Notice that selecting 'Format Cells' brings up a submenu that allows you to change the font style size and color. You can also change the formatting to currency ($) or percentage (%). You can also increase or decrease the number of decimal places () Note that even if you restrict the number of decimal places that are displayed the full accuracy is still used in calculations: In the example the value in cell C2 is actually 3.14 but has been formatted to show only 1 decimal place. The calculation shown in cell C3 uses the actual value.

Note that even if you restrict the number of decimal places displayed the original accuracy is still used in calculations. In the example the value in cell B2 is actually 3.145 but is formatted as a number to 2 decimal places.

You can explore the various options. I've used the 'currency' number format to add the '$' symbol and two decimal places. I've also changed some cell alignments and font sizes.