My watch will only let me see the time in green numbers

1. Forced Reset your watch to clear any confused software. Press and hold the Digital Crown and side button (together, about 10 seconds) then release the buttons and let the watch reboot.
2. Try changing to a different watch face. Change your Apple Watch face - Apple Support
3. To display all the available apps, short press on the Digital Crown. Your photo looks like you have your finger clamped down hard on the poor unsuspecting crown.

It would also appear that your device may not have a good charge on it. Normally a Watch that requires charging would have the screen appear like that, only with a red lightning bolt to the left of that. Place the device on the charger, and I recommend that you use the force restart procedure that Branta_uk provided.