Demetrio --
You will need to add the Insert Page Break button to your Quick Access Toolbar. To do this:
1. Launch Microsoft Project and open a project.
2. Click File > Options > Quick Access Toolbar.
3. Click the Choose Commands From pick list at the top of the dialog and select the All Commands item.
4. Select the Insert Page Break item in the resulting list.
5. In the list of commands on the right side of the dialog (in the Quick Access Toolbar), select the button BELOW WHICH you want to add the Insert Page Break button.
6. Click the Add button.
7. Click the OK button to close the dialog.
To insert a manual page break, select the task that you want to appear at the top of the new page and then click the Insert Page Break button on your Quick Access Toolbar. Hope this helps.