As already mentioned, traditional level design doesn't requires any programming knowledge, unless you consider scripting programming, and afaik its not that often its required of people who work with level design (varies from place to place obviously)
My best advice, apart from finding an engine you like and reading a bunch of tutorials, is to play a lot of games and see how people set up situations and try to figure out how things were set up. Also if you're thinking about this on a professional plan, then trying out as many different engines as possible is always good idea, since it'll make you well prepared for the eventual point where you need to learn how to use some new stuff.
Also these days having some good experience in a 3d modeling app such as Max or Maya is a really big plus, and in most cases essential.
I have no idea where to find tutorials these days, but thats the way most people start ![]()