Sorry you can't upgrade to Business. You will need 2 programs. The Business program and a personal version.
You need to buy Turbo Tax Business, not to be confused with the personal Home & Business version. Home & Business is just for personal returns that need schedule C for self employment. You can have both Home & Business and the separate Business program installed at the same time.
You can buy the stand alone do it yourself Business Download program for Windows here (it is not available to do online or for Mac).
https://turbotax.intuit.com/small-business-taxes/cd-download
