… no beginner's task.
no 'automatism' built-in in Motion, nor FCPX
what you're looking for is called Kinetic Typography
as a start watch this tutorial
No one knows Motion (or teaches it) better than Mark Spencer. Here is exactly what you need.
In Preferences > Appearance towards the bottom you'll see Status Bar. Make sure "Frame Rate (only during playback)" is selected. It will appear at the top of the canvas in the same bar as the Render and View menus (but over towards the left side) when the project is playing. It will give you a good idea if the project is playing slowly (less than the frame rate of the project) or up to speed.
Motion frequently plays slower than the chosen frame rate of the project. This variance in playback can easily and certainly throw off your judgment. If this is happening and you need to verify the speed of an animation, Export (share) and play it in Quicktime Player. As you work the project, you can always keep saving over the same temporary video file and simply throw it away when you're done with it. Also, changing the export render settings to ProRes proxy, you will create a much smaller file (don't bother with H.264, it takes much longer to render than ProRes and interfere with "workflow".)
To avoid confusion from slower frame rates, you can also do a RAM Preview (Mark | RAM Preview | All/Play Range).
When you do that, it's playable in the timeline at full frame rate. It caches, so it's smart enough to re-use rendered bits in subsequent renders if nothing has changed.
This will be much faster than exporting it, I would imagine.