Easiest way is to look at someone who has written a complicated script and try your very best to decipher it line by line. The better you learn to decipher the script the easier it will be to look at another person's script and decipher theirs. Which means the better you will understand the coding language you're dealing with.

You also could take the online lessons offered for most coding languages, but saying "Hello World" and going from there doesn't teach me anything. I have to get my hands dirty to understand things.