I can't trill my "r"s. How do you? And how will it affect my Spanish and Czech?

I'm in High School, and I will be taking Spanish, of course, because it's required for the college I want to get into. However, since I won't be learning it unitl Junior and Senior year, I have 2 years to learn a bit of Czech, a language I want to learn personally. I've noticed that in both Czech and Spanish, the "r" can be trilled. How do you trill the R? And please, don't just say "put the tip of your tongue and blow air". I can't do that. Growing up, I always used to make a machine gun noise by doing something similar, but my mother told me never to do it again because it was annoying, and now I can't do it. What I can do is make a sound back in my throat that sounds like a trill, but it's not fast to do, and doesn't sound similar enough. And how will not being able to trill the R affect my speaking of the Czech and Spanish?