rdfosho

hey im new to music theory but i have spent alot of time learning songs and just playing my guitar and im really good at it and can play about anything but i want to write my own songs now. And i dont know how. Basically all I need is to know what notes I can play over what chords and I will be good. So for example if I play a d5 power chord what are all the notes i can play over that chord. Thanks