Hi Raviteja,

DescriptionLearn how to create an Event in Lightning Experience

ResolutionTwo ways to create an Event in Lightning Experience. 

Option 1: Through the Calendar

a. Go to Calendar tab
b. Click "New Event" (in the right side panel)
c. Populate the required and available fields.
d. Click Save.

Option 2: Through the Record
 
a. Go to the object (you want to create the event with)
b. Select the object record (you want to associate the record with)
c. Select New Event
d. Populate the required and available fields.
e. Click Save.

Note: These are the available fields when creating an event:

Required Fields:

1. Subject (Name of the Event)
2. Start Date
3. End Date
 
Available Fields but not required:

1. Name - Contact which the event is associated to
2. Related To - Account/any objects which the event is associated to
3. Location
4. All Day-Event 

If a user wants to access events in lightning then he will need at least Read access to the following Event fields: 

• All-Day Event: (IsAllDayEvent)
• Subject: (Subject)
• Start: (StartDateTime) 
• End: (EndDateTime) 
• Go to the profile of the affected user within Setup.
• Edit the Field Level Security for the Event object.

Ensure that there is at least Read access to the fields listed above.


Take a look here Events not visible in LEX Calendar despite showing on Classic Calendar https://help.salesforce.com/articleView?id=000239627&type=1



Hope this helps.

Kindly mark this as solved if the reply was helpful so that it gets removed from the unanswered queue which results in helping others who are encountering a similar issue.

Regards,
Nagendra