Conditonal formatting dates

I am trying to format a training spreadsheet but really struggling. I have a list of employees and the dates they completed specific training modules. 

What I'm wanting to do is format the dates so when their training is in date the cell (the cell that displays the date the training was originally completed) is green, Amber when the training is due to expire in 90 days, reddish 2 weeks before training should expire and red when it has expired. Some training needs doing every year, others every 3 years and finally some every 5 years. All employees have different dates each training has been completed. At the moment the spreadsheet I have been given has no formulas on it at all. 

I just can't seem to get anything to work and must admit I've never done any conditional formatting where dates are involved. If anyone has any ideas of something I could try I would greatly appreciate it. At the moment the spreadsheet I have been given has no formulas on it at all.