How do you become a spell casting wizard?

To be honest, the term "wizard" doesn't really exist. Both male and female spell casters are usually called witches. One can become a witch by practicing the religion Wicca for a year and a day. However, one does not have to be a Wiccan to cast a spell. All you need is the spell and the materials required. Just follow the directions, and you've cast the spell!

A Pagan Perspective

Just for the record, not all people who call or consider themselves Witches are Wiccan. Nor do all people who cast spells call or consider themselves Witches.

Casting a spell is simply the manipulation of naturally occurring powers (magic) by the hand and will of a practitioner.

Anyone willing to do the research, and practice is capable of casting spells. Part of that research is learning to use the "power" in an ethical and honest manner.