If you don't know how to add custom widget into your Zabbix - check this tutorial https://www.zabbix.com/documentation/current/en/devel/modules/tutorials/widget#add-a-blank-widget-to-zabbix-frontend
"Show global" flag simply lists all your dashboards that have status "Shared" Use "trigger" form to add custom links (condition field does nothing and "value" field should be filled with dashboard id)

