Question about Tabs Input Properties


I am new to ionic and am semi familiar with angular2 now as I have been using it for a few months. I have noticed this often in the ionic documentation but have never implemented it because I was confused. Lets say I have a tabs bar, how would I implement the highlight underneath it. I see that it has a “tabsHighlight” and I was wondering if I could be shown some code or told where exactly I put this to turn it to true. Do I put it directly into the html or in the typescript or what? Thanks!