Who can write contracts in Illinois

[Jerome Lanier]

This is a very basic question but I want to be certain. I recently had someone tell me that if I write a real estate contract for a property in Illinois without a license I can be arrested. This person has some experience in real estate and they were very adamant about it, however it seems to me they were unsure and guessing. Can anyone in confirm if I can write my own contracts in Illinois without having a license.  

Thanks.