Display error messages in dashboard

Hi All,

We have a requirement of displaying error message for a mandatory field.

For ex: We have few search fields and a connection refresh button(renamed as show) clicking on which will trigger queries.

If user doesn't enter supplier name and clicked on show, we need to display an error message on dashboard that it is mandatory and it should be filled.

Can any one please help me in achieving this.

Thanks,

Vennela