Questions regarding Hard Money Lenders

[Mark Libario]

How do HML's work? If I bought a property that costs 150,000$ Can i fund it 20% through HML's and financed by the bank the remaining 80%? Let's say i got 30k from HML's for 7% interest= 175$/month. When do I pay the 30k? Or do i just keep paying interest and until I sell the property and give back the 30k? Is this a possible way of financing too?