In the top menu, click Extensions and then click Template Manager
In the tabs at the top of the page, click the Options tab
Under the Templates tab, find the following setting:
Preview Module Positions
Enable the preview of the module positions in the template by appending tp=1 to the web address. Also enables the Preview button in the list of templates. Please refresh the page after changing this setting.
Click Enabled next to this option, and then click the Save & Close button at the top of the page.
Once again, in the top menu, click Extensions and then click Template Manager
Now that we have the Preview Module Positions setting enabled, you will see a preview icon next to your Site Templates. Click the preview icon next to the template you would like to view.