The only safe way, is to either learn regex syntax, or hire someone to do it for you.
First off, you need delimiters to tell regex where things start and stop. Since [ can actually be a valid delimiter, your expression is literally matching only the text in between [ ] and using those brackets as its delimiters.
I use # because I find it to be the character I have in matches the least which makes it easy to identify things and makes for the least amount of escaping. What I use is preference but you can use any n
on-alphanumeric, non-backslash, non-whitespace character. Just remember that whatever character you use for a delimiter must be escaped if used in the expression.