to calculate the difference between two dates, in years, use:
=DATEDIF(B6;NOW();"y")
Notice that now() is the computer date, and in B6 is the date value entered.
"y" can be replaced with "m", or "d", or "md", depending on your needs.
Have you ever tried to study an well made excel function dictionary , with most of the functions explained?
I recomend you http://www.xlfdic.com/
For sorting data, you better organize data in a named table, you can do lots of things with your data; a formula cannot sort data in a table.