How do I place a lien against real estate property?

Well, what's the lien for?

I loaned someone a large sum of money.

You will have to go to court and get a judgement, at that point you have a lot better options than getting a lien, you can garnish their pay, if your state allows for this, you can attach their bank accounts, and of course get a lien on their property in many areas

You need to file suit against them and obtain a judgement first,