if else query help

Hello all,

I need to write a query that will pull information from table2 if
information in table1 is older then xdate.

My laymen example:

SELECT table2.date, count(table2.name) as count
WHERE table1.startdate > 2 weeks
AND table2.submitdate > 2 weeks
;

So i Guess my real questions is how do I determine the age of an entry to
another table?