Summer fling

So I like a male friend of mine, and I have no clue if he likes me back. And his grandparents live like right across the street from mine. And they live on a lake, so the last couple summers I’ve hung out over there with my guy friend and his family, but this summer I kind of want to branch out and meet new people up there and maybe have a small summer fling. The thing is though is that I’ve never dated before or had a boyfriend so I have no clue if that would be a good idea or not. Also I don’t want to totally brush off my friend because they’re only up on the weekends. I’m just really confused especially if my friend likes me or not. And my grandma wants to set me up with one of her friends grandsons, but I’ve never met them before and my grandma doesn’t know how old they are so her plan might fail if they’re older than 16-17 because I’m 15 and that would just be awkward.