Questions about my Daewoo

First off i cought my Daewoo used it is a 1999
Ok, it has been in the shop .. we have changed the cam sensor and the O2 sensor and the timing belt we also had a oil leak ..
ok so all that done but the check engine light came back on
so we check that .. we are now going to have to change the EGR valve.
Does anyone have a clue how to do this .. my hubby wants to do it and save the money of the mechanic again ..
also i have seen here that some parts are under recall how do i do that when my car is used ???
Thanks for any help ....