Luiz --
In your previous reply, you indicated that your organization is using Project Online. This means that only application administrators can check out and edit resources from the Enterprise Resource Pool.
If you ARE an application administrator for your Project Online instance, launch your web browser and navigate to Project Web App. Click the Resources link in the Quick Launch menu to navigate to the Resource Center page. Select the checkboxes to the left of the resources whose calendars you want to edit, and then click the Open button in the Resources ribbon. The system will launch Microsoft Project, connect it to Project Online, open and check out the selected resources, and display them in the Resource Sheet view. From here you can edit the calendars for the checked out resources. When finished, save the latest changes to the checked out resources, and then close and check in those resources.
If you ARE NOT an application administrator, then one of your app admins will need to perform the preceding steps. Hope this helps.