Assuming that row 1 contains headers, select rows 2 to 143 or further down. The active cell in the selection should be in row 2.
On the Home tab of the ribbon, click Conditional Formatting > New Rule...
Select 'Use a formula to determine which cells to format'.
Enter the formula
=AND($K2<>"", $K2<=TODAY()+60)
Click Format...
Activate the Fill tab.
Select yellow as fill color.
Click OK, then click OK again.
Repeat these steps, but with the formula
=AND($K2<>"", $K2<=TODAY()+30)
and red as fill color.