I can somewhat relate to this as I've struggled to do certain things, I've found that starting at basics helps me, as its easier to have confidence for something thats mundane and not too important if it fails. I've been wanting to try casting a spell from a game (to learn more things) and can certainly relate that to the fireball you mention. My plan is to find a precise spell from a game and try to mimic the actions to produce it, i.e. copy the hand movements of the caster, maybe even try and make the noise for it with my voice as well and expect the casting effects to appear around me.

For lighting rooms for instance I would try the light spell from Skyrim (forget its name). I'm sure theres probably plenty of fireball spells in games though I guess that useful only if you play them. This is something I have no actual experience with though, just something I want to try and my ideas on it.