Installing Spanish Language Pack (Error Results)

[bsort]

Thanks for the link. I have downloaded it to my PC - what next?

I would like the option to see the payment page in either Spanish or English - how does this work?

[torvista]

I think you may be a bit confused here.
You don't have your Zen Cart in one language or another (although you can force that), there is one shop and each language you add gives the user the option to select the language they want.
All pages will be available in all the languages you have added - ensure the languages sidebox is enabled so the user can choose.