Income-Expenses=Net Income?

I am a bit confused. Revenue is the entire income generated from sales, etc. Expenses (suppliers, employees, taxes, etc.) are paid from the revenue. What ever is left (net income) goes to shareholders. But what does the company use the shareholders equity for (be specific)? Because when they take their revenue and subtract expenses, they are including paying their suppliers with their income, and i thought that they used the shareholders equity (your money) to pay the suppliers? Could someone clear this up for me? Thanks