Welcome to the portal.  First we are going to need some more info of course a picture is always helpful especially when diagnosing issues. What medium are you using what size container any drainage? Air flow another biggie. If you are already getting yellow edges might be too hot of soil or too much on nutrients if hydro grown. Kinda lights are you running and how close this is the kinda info needed to help, but your in the right place to learn as we still all do. Glad to have ya aboard