Property Tax Sale: Cook County (IL)

Hello All, 

I am a young real estate investor, who just purchased her first tax lien. Despite what I have read online, the process post-sale is still rather confusing to me. The problem is tax sales are so specific to the county. My questions are: 

1) What does a buy sheet look like/ where can I find mine? 

2) what is a 5% certificate?

3) for future tax sales, what is the best way to find info. about the parcel numbers, other than the treasurer website? 

Thank you for your assistance, it is greatly appreciated. 

Emma McCarthy