I've helped thousands of people in my 20 years as a family law attorney get their divorce process started. I've also helped them walk through the divorce process. Although starting the divorce process from an emotional standpoint may be a difficult thing, from a practical standpoint, it's really not that hard.
The thing you need to do to start your divorce process is file something called a petition for dissolution of marriage. In some jurisdictions it may be called a petition for divorce. In your petition for dissolution you're going to be telling the other party and the court what it is you want to happen as a result of the divorce.
A broad outline of what you will be including in your petition for dissolution is you're going to be making statements or proposals about how you want to share children as far as custody and parenting time; the division of property and assets and spousal maintenance or child support.
You need to check the laws...