I cannot get my watch to update

Assuming your watch is capable of running watchOS 8 (this is when you own a series 3 watch or later) see this link and follow the instructions provided

Update your Apple Watch - Apple Support

What model of phone is it and what version of ios is it running?

What model of watch is it and what version of WatchOS is it running?.

What troubleshooting steps have you tried?.

What errror messages are you receiving?.

What series watch is it?