Quick Formula For Reporting Last Contact Date

Quick Formula For Reporting Last Contact Date

I need to create a simple formual to create a simple report for sales contact reporting.
 
First I create a custom date field and call it "Last Contact"
 
Then if this  Last Contact date  is added to a formual and if the date falls into the last  < 30 days the contact is = to  what I call  "Green Light"
 
If this Last Contact  date falls in between >30  < 60 days  they are = "Yellow Light"
If this Last Contact date field is > 61 Days  they are = "Red Light"
 
Report then says show me all Greens or Yellows or Red Lights
 
 
Can you help with what needs done to include the formula and the custom filed types and names?
 
Many variances I can think of once I get the formula and by the way I would like to include "Last Contact"  into my import Excel sheet as a mandatory field
 
Thank You for the help!