Button to Launch another App on Android and iOS Phones?

Dear Experts,

So I converted my web site to an Android app using AppMySite’s service. So far everything is great but when launching my app, there is a button that requires the user to download ClassIn on Google Play or App Store if they haven’t downloaded ClassIn, the button doesn’t launch.

Is there a way to click the button on app and launch the Google Play and App Store?

Thank you!