How do I secure a personal loan with property as collateral

I am extending a personal loan to a friend in exchange for a lien on his commercial property as collateral. What does this entail? Do we need to record with the county? Change the way the title is held? Notify the First lien holder? He says there is about 200k in equity and the loan is for 150k. Can you please advise how to do this and tell me if you think it is wise. Thanks