promisary note as earnest money,proof of funds letter

I’m new at this wholesaling thing and I want to assign my contracts to start. I have no money and I have read where you can use a promisary note as earnest money, How can I do this and assign the contract since I won’t “actually” be giving them money at closing. Does the person that I assign the contact pay the earnest money stated in the promisary note? Can anyone help? Also how can I get a hard money lender to send me a proof of funds letter or e-mail me one?