To add a new task, please go to CRM->Activities->"New Task"
OR
CRM->"Add New" (Top left button) -> "Task" option in drop-down.
You will be asked to fill the following fields:

• Assignee*
• Subject*
• Due date
• Reported By
• Lead*
• Status
• Priority
• Send Email Notification
• Show In Calendar
• Description

After completion of the fields press the Save and Close button. Note: Starred (*) options are required.