I'd venture that if you have to ask such a generic question about how to start a startup, you're probably not well equipped to do so.
My suggestions are as follows:
1. do 3-6 months interning with a small very early stage startup
2. find someone else to execute your idea whilst retaining a % equity
3. look to find co-founders who can execute the idea, stay involved but focus on your skill set (if it's relevant)