How to add custom template?

[flc85]

Hello,
Sorry but i don't understand how to enable custom template?
i put in the dashboard.yaml
webpage: type: custom:button-card template: icon_template icon: mdi:web tap_action: action: call-service service: view_assist.navigate service_data: device: '[[[ return variables.var_assistsat_entity ]]]' path: /view-assist/webpage
in the Master Configuration Dashboard Options i add the menu : webpage
i reboot all and in the menu i have an orange icon
Please what's wrong?

[dinki]

This is very hard to read due to formatting. Please edit and use three ` symbols on the first line, then the code then three more for the last line.

What are you attempting to do? Not clear.