CRM+ has a built-in calendar, which can be opened from several places where the little calendar icon shows it.

After opening it, you will see your current week.

Current day is marked by a gray layer, while the current time-slot is yellow.

You can navigate using the mini calendar icons, or by the arrows next to the Go to current date label.

When using CRM+ as a multi-user environment you can also choose the user whose calendar you would like to see.

There are two types of calendar entries. The first one is the reminder, which you can read about at the reminders wiki.
These are show as a blue range.

The other type is the “range mark” entry. This is used when you don't want to set up a reminder with a history (for e.g.: vacation,private stuff), but you do want to indicate that you are not available at that time. These are shown as a gray range. These also appear in your reminder list.

To add a new range mark entry, simply click on the starting time slot at that particular date, or press the range mark button (in this case you will have to manually fill the date and time).

You will see the new range mark window:

Here you have to set up the date, start time, and and time. You have to choose the contact (if it's a private thing, choose yourself from your company), and set up what you will do, or any kind of additional information you need.

CRM+ calendar works with time-slots.

It doesn't let you create two events at the same time (as you cannot be at two places, and do two things at same time).

So if you try to create an event that is happening at the same time, CRM+ will warn you, and don't let you do that: