On Mac: 

• Сlick on a Calendar icon in the toolbar to view all events
• Or select a contact and click Calendar bookmark in the bottom of the Info panel to view events assigned to the contact

On iPhone or iPad:

• Go to the contact list
• Tap on a Calendar icon in the toolbar to view all events
• Or select a contact and tap on a Calendar bookmark in the bottom (in the Detailed Info panel for iPad) to view events assigned to the contact

On Mac: 

• Сlick on a Calendar icon in the toolbar then click "To Do" bookmark to view all events
• Or select a contact and click "To Do" bookmark in the bottom of the Info panel to view events assigned to the contact

On iPhone or iPad:

• Go to the contact list
• Tap on Calendar icon in the bottom of toolbar and tap "To Do" bookmark to view all tasks
• Or select a contact and tap on a "To Do" bookmark in the bottom (in the Detailed Info panel for iPad) to view tasks assigned to the contact

On Mac: 

• Open Calendar / To Do list
• Double-click on a preferred event / task
• Change event / task title in the corresponding field
• Type notes in the "Notes" field
• Click "Done" button to save changes

On iPhone or iPad: 

• Open Calendar / To Do list
• Tap on a preferred event / task
• Change event / task title in the corresponding field
• Type notes in the "Notes" field
• Tap "Back" to save changes

On Mac:

Option #1:

• Open Calendar / To Do list
• Double-click on a preferred event / task
• Activate checkbox near the "Due Date" (if available)
• Specify the date until when the task should be completed or date when the event begins
• Click "Done" button to save changes

Option#2:

• Open Calendar
• In the window that appears click & hold the event
• Move it up or down to change the Due Date

On iPhone or iPad:

Option #1:

• Open Calendar / To Do list
• Tap on a preferred event / task
• Activate toggle for "Due Date" (To Do list only)
• Specify the date until when the task should be completed or date when the event begins
• Tap "Back" to save changes

Option#2:

• Open Calendar
• In the window that appears tap & hold the event / task
• Move it up or down to change the Due Date

Please note, you have to specify the Due Date first to enable the Reminder option. Please ref. to "How to set a due date".

On Mac:

• Open Calendar / To Do list
• Double-click on a preferred event / task
• In the "Remind" field specify how long before the due date you want to be notified
• Click "Done" button to save changes

On iPhone or iPad:

• Open Calendar / To Do list
• Tap on a preferred event / task
• In the "Remind" field select how long before the due date you want to be notified
• Tap "Back" to save changes

Please note, you have to specify the Due Date first to enable the Repeat option. Please ref. to "How to set a due date".

On Mac:

• Open Calendar
• Double-click on a preferred event
• In the "Repeat" field specify the repeat period
• Click "Done" button to save changes

On iPhone or iPad:

• Open Calendar
• Tap on a preferred event
• In the "Repeat" field select the repeat period
• Tap "Back" to save changes

On Mac:

• Open To Do list
• Activate checkbox near the preferred task name

On iPhone or iPad:

• Open To Do list
• Swipe right on a preferred task
• Check it off

On Mac: 

• Open Calendar
• Double-click on a preferred event / task
• In the contacts section click on "+" button
• Select person from the contact list
• Click "Done" button to save changes

On iPhone or iPad: 

• Open Calendar
• Tap on a preferred event / task
• In the contacts section tap on a "Assign Contacts" button
• Select person from the contact list
• Tap "Back" to save changes

 On Mac:

• Open Calendar / To Do list
• Double-click on a preferred event / task
• Click "-" button near the contact name you would like to unlink
• Click "Done" button to save changes

 On iPhone or iPad:

• Open Calendar / To Do list
• Tap on a preferred event / task
• Swipe left on a contact you would like to unlink and tap "Trash" button 
• Tap "Back" to save changes