Gustaf Alströmer, a Y Combinator group partner, explains how to get your first customers for a startup. He advises Founders to do things that don't scale, and that they should be the ones doing the sales in the beginning. He references Paul Graham's essay about the early days of Airbnb and the startup curve to illustrate his points. He emphasizes the importance of understanding your customer, writing clear and concise emails, and showing the social proof of your team and product. Finally, he encourages Founders to stay the course, not give up, and have a passion for solving customer problems.