To make a dashboard mobile with Tableau, you don't need to do anything specific. Simply publish to Tableau Server as usual, and Tableau will recognise whether or not you're using the Mobile app. Dashboard choices include iPad, desktop, and automated, as well as the ability to customise the size of your dashboard.
You may access Tableau Server directly from your mobile browser, without using the app. Views and dashboards instantly operate on your tablet without any further writing or design adjustments.