Hi Linda! No your question is not silly! It's a very important one.

The guitar is tuned to "Standard Tuning" - which is, from low string to high string, E A D G B E.

You might be confusing the tuning with the key of the song. In Wild Horses, the verses are using the key of G, while the chorus uses the key of C. The key of the song lets you know how the chords relate to the vocal melody and tonal center of the song.

As a beginner, I wouldn't worry too much about what key the song is in.
Just focus on getting the guitar tuned to Standard Tuning, and work on getting familiar with the chords and your strumming.

I hope this helps!
Mike