Most people on this site wouldn't recognise a spell if it jumped and bit them!
You can write your own spells! For instance, most people have cast a spell at some time without knowing what they were doing.
If you have blown out the candles on a cake, and then made a silent wish, you have cast a spell. Pulled a wishbone? That's another spell.
So, a spell is a "ritual", followed by a "wish" (intention) to do, or change, something in your life, or in your surroundings.
A spell can be very simple, or very complicated! You will learn as you practice casting.