That’s simple; go to Project Overview or Tasks and Communication pages in a project and press Set New Task button.
Here you will have to enter the name of task and the officer in charge of it and formulate the task itself. You can fill in other options like priority level, completion date and estimated duration of work when and if necessary. Beside that, you will be able to attach necessary files to the task or to limit the task visibility for the whole company or some its employees.
Remember: if willing to have the set task known to project members ASAP, do not forget to subscribe them to e-mail notifications. As soon as you’ve clicked on Create Task button, all the subscribed members will receive e-mail message with the description of task and links to the task page in the Worksection account. Also, all the subscribed members will receive e-mail notifications every time someone adds a comment or subtask to the task in question.