You would have to get a platform swap (upgrade to CS6 in this case, since CS5 isn't sold anymore), or buy the new Photoshop CC subscription. For detail on the swap follow this link: https://helpx.adobe.com/x-productkb/policy-pricing/order-product-platform-language-swap.ht ml
You can find the CS6 upgrade here: Creative Suite 6. Click buy and then select upgrade.
Thank you both for your responses