Wonnie, 

This is one of those situations where it will pay to visit a tax professional.  Depending on how you set up your company you will either be able to take out payroll taxes from your pay check, or pay quarterly esimates, or possibly both.    You also need to be aware that you are now 100% responsible for your SS, Medicare, and Fica taxes, of which your employer previously paid half .  And if you miss something, or your payments are late, not only is the tax due, but penalties and interest.    This is a situation where the saying, "You don't know what you don't know" applies.