The phrase "add calendar" is correct and usable in written English.
It can be used when referring to the action of including a calendar in a digital application or system, or when suggesting to someone to create or include a calendar.
Example: "To keep track of our meetings, please add calendar to your list of tasks for the week."
Alternatives: "insert calendar" or "create calendar".
Simply click the icon in the top left of the phone screen, then the cog -> Add Calendar.
We also do it to develop new product features such as e-mail categorization to organize similar items like shipping receipts in a common folder, or to automatically add calendar invitations.
But increasingly, advertisers are tailoring ads to phones by taking advantage of elements like their ability to track location, make a call, show maps with directions and add calendar alerts.
Pebble says you can add calendar alerts, Facebook Messages, tweets, and weather alerts to the notifications; I do wonder what sort of weather alert (short of a tornado) you'd want to know about, but in principle it's putting everything just where you want it.
iPod Touch Firmware 1.1.2 Released: Add Calendar Events [MacRumors.com].
People use it to send voice-to-text emails and sms messages, send Twitter messages, add calendar items, etc.
On the next screen, select the Add Calendars option and give the new calendar a name like Spam, Junk or something therapeutically snarky.
For this reason, I add calendar-year dummies to (9) in the fourth specification.
Neither work perfectly yet; I had problems submitting Twitter messages with URLs and with adding calendar events with specific times.
In the coming weeks, Markspace will be adding Calendar, To-Do list, Notes, and Bookmark syncing, along with fancy features like SMS backup and wireless, proximity-based syncing.
MatchTag's added calendar feature makes it easy to not only find activities you know you like but also stumble upon new ones.
