Hi, Connie. This is not a job for a do-it-yourselfer. Since you have to be opening a load-bearing wall, you have to make adequate provision for carrying the roof load, etc. during and after construction. You also will have to provide cantilevered joists to support the floor load. Start by contacting a qualified architect or a major construction company with an architect on staff. There has been a lot more than one bay window built where the load caused the bay window to sag away from the house and caused numerous problems. Be very careful in choosing your architect and construction company.