Easy enough job for many but you don't do it often unless your in the trade.

There are more then a few youtube videos on the subject.. worth doing rather then stuffing new parts no matter where you get them.

Here are a few.. worth the eductional time.. 

https://www.youtube.com/watch?v=ts6vX8csaTA

Using a Power steering Filter..  https://www.youtube.com/watch?v=-dpA4gy_2Ug