Legal Question in Appeals and Writs in California

It is not a simple process that any of us can give an easy 1,2,3 step instruction. You need to the research at a law library or hire an attorney. Sorry.

You need to provide more information. There are all kinds of writs, such as writs to the trial courts from the Court of Appeal, and writs of mandate from the superior court to administrative agencies. You don't even tell us whether it is civil or criminal.