The Hobbit came first. The Lord of the Rings follows on from it, albeit a goodly number of years later.

In the example given, Bilbo stumbles across the ring in The Hobbit where it is not a massive plot point (from what I remember), but it becomes the crux of The Lord of the Rings. That's all the example means.

Think about what your plot is. And then write a story that sets up that plot. It may be something subtle (like the LOTR example) or it could be something much more direct and obvious.

Hope this helps.