Can you tell me how i can take st john's wort for first time, what quantity to take it in for moderate depression?

MAOI: The way st. John's wort works as an antidepressant is by a mild MAO inhibition like older antidepressants from the 50s and 60s. The most common dose in clinical trials os 300mg three times a day.

I encourage you to: consider having a psychotropic medication prescribed by a physician. That will insure more standardizes dose and product purity.