Construction/Rehab Financing

Hey all!
I’m new here and have a question. I purchased a home for $180k and want to do a renovation. If i do a nice renovation the ARV should be around $350k min. I would like to borrow $100k for the renovation. How do I do this and what are my options?
Also, can someone please explain what a hard money lender is?
Thanks a bunch!

ps - i’m in Atlanta