How do I highlight my hair with lemon juice?

I know how to put the lemon juice in my hair, but am I supposed to take a shower before? Am I supposed to blowdry it, then do the lemon juice? Or do I leave it wet, and add the lemon juice? Thanks. :)How do I highlight my hair with lemon juice?
it doesn't matter just put the lemon juice on your hair and go outside for a few hours