if I use the calendar on I phone the items aren't showing on watch

Taken from this page;

Check and update your calendar on Apple Watch

Change how you view your calendar

To switch views, open the Settings app on your Apple Watch, tap Calendar, then tap an option:

• Up Next: Shows your upcoming events for the week.
• List: Shows all your events from yesterday through six days from today.
• Day: Shows just the events for this day.

To

see the whole month, tap < in the top-left corner of any calendar in

List or Day view. Tap the monthly calendar to return to Today view.

To see another day, swipe left or right if you’re in Day view; if you’re in List view or Up Next view, turn the Digital Crown.

To jump back to the current day and time, tap the current time in the top-right corner of the display.