@wiggydiggy
It's a bit of a misnomer, at least in the Android App.
You can either:
pick a point on the map and longpress. You'll get the option to "Start here" or "Navigate to here".
or
Type in the "To" box. You'll be offered the same options.
In general, it's probably worth remembering that the app lacks all the functionality of the website. It's fine for short, on-the-go planning but the website (available on the phone too!) is superior.
The ideal combination is to detail plan on the website, then navigate on the app.
For example, "Markers" (our own POIs) are available on the website but not currently available on the app.
As well as differences between the website and the app, there can be differences between the Android & IOS apps, at least in the exact steps to follow.
It would be helpful to be clear on if you're using the website or which app version.