Foreclosure Title search ( liens & Mortgages )

[Adam Rivera]

I am new to the Real Estate foreclosure world. I have taught myself a bit on how to do TItle search on my own but I am no professional and I am still confused on the Order and Hierarchy of mortgages. If I were to buy a building that is in second mortgage foreclosure. Would I have to worry about the First mortgage (below the Second Mortgage ) or the third mortgage ( Above the Second mortgage )? Also I am a bit confused on. At what point do files matter to me as a buyer is it the date of the mortgage or the date of the foreclosure because I noticed some foreclosures can go on for a long time which gives the property more time to add more liens and such to the record pull? 

Can somebody Explain things I have to look out for and the order/Hierarchy. I live in illinois / Chicago The response doesn't have to be related to my state laws I just need over all Info Basic rule of thumb.   

Thank you,