Hi Tsimp85,
Welcome to the Apple Community
Apple support have articles online (links below)that can help guide you.
How to add complications to a Watch Face:
Customize the watch face – Apple Support
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More info. if needed:
To scroll through all the Watch faces online, and see all the "complications that are available for each:
Apple Watch faces and their features – Apple Support
To scroll through the Watch Faces on your Watch:
Explore the Face Gallery on Apple Watch – Apple Support
NB: In some countries not all the watch faces may be available.
All the best :-)