AEM 6.1 Checkbox Enable/Disable tag attributes

I have created my first AEM component. The functionality for is very simple. Drop on page component that will generate a text with a URL and option to be able to open in a new window.

<a class="btn" href="${properties.ctaUrl}" target="${properties.ctaNewwindow}">${properties.ctaLabel}</a>

How do I specify target="_blank"? ctaNewwindow xtype is checkbox

Thank you very much for your help, T