In my opinion there is no reason to worry about the subjunctive mood at your level of English. It’s not a particularly important thing to know how to use. I can’t imagine that anyone will ever misunderstand you if you don’t use it. This is an example of the subjunctive mood: “I wish I were rich”. Because you are describing a wish you write “were” instead of “was” which would be the correct thing to write in a normal sentence like for instance “I was born in China”.