This Apple ID has not yet been used with the App Store. Please review your account information

I just got a new imac 27inch late 2013, the computer has an update and I created an account, the problem is when I try to access to the appstore, this pop up and I cant update or install free apps it tells me, "This Apple ID has not yet been used with the App Store. Please review your account information." In Spanish "Este Apple ID no se ha utilizado todavía en App Store. Revisa tus datos" What can I do? Im not interested in put credit card info because this computer is where i work, and is necessary install the update.

thanks!