First prepare a return that matches what was filed for Illinois. Make the corrects that you want to reflect on the amended return. 

Go to Miscellaneous Forms > Amended Return (1040-X) > Complete the General information and then > Illinois Amended Return - HOPEFULLY the two columns are now completed with the Original and Corrected amounts. 

https://proconnect.intuit.com/support/en-us/help-article/federal-taxes/amend-individual-return-1040x...