@blueberrymama - I misread your post. I thought your daughter had the Watch but just realized that YOU have the Watch.
My (now deleted) directions were for your daughter who is running the Dexcom App to have those numbers onto the Watch that SHE is wearing.
However for your situation where you get the numbers via the Dexcom Follow App and then want to have those going to the Apple Watch - I do not know. That situation is not what I have seen.
You could try going into the Watch App on the phone and see if there is something there for Dexcom? If it was your daughter with the Dexcom Mobile App - this is how she would do it. But I don’t know if this would work for you with the Dexcom Follow App.
And “ASK AWAY” if you have any Dexcom specific questions. There actually is a bit more of practical knowledge to making good use of the Dexcom then what you get in basic training. Likely any Dexcom questions you might have can be answered here.