date function formulas

Hi all,

I have been given the task of making a new speadsheet for staff auditing purposes.

The sheet is done and looks good but i need to add some further info that is just beyond my knowledge........

I have a column for the date i need excel to automatically change this date if any info is updated, I also need it to forwarn of expiry 4 weeks to amber and 1 week to red warning but i need it to keep original date in the cell.

I've looked on here and found many similar solutions but having tried the formula didn't work.

Cell column is R# for the date and i want the cell background to change! columns D to Q have changeable data but i want R to auto update if the cell value is changed in D to Q.

Please talk to me like a six year old so i understand it!!!lol

Many thanks in advance.

PS is there anywhere i can learn about all these sorts of thing or study them free????

Tony