Search it on the site. There are so many posts detailing on how to do this. Good luck.
I recommend you to find articles and to do it firstly step by step.
Here are few ones that i have found for you:
You can find ones as well, and do it carefuly and put energy into your spells. I am sure there are great articles about making your own spells in this site as well.
No one looks it up themselves before they ask a question anymore. lol