This is due to your role security settings. Please talk to your manager in order to increase your access to the system.
The owner/manager will need to change your user role. If you can't add jobs this means you are 'Engineer' role, you need to be changed to 'Engineer with diary' this will allow you to edit the diary.
- Go to Company settings
- Click Users
- Click View next to the user you want to change the user role of
- Within the section called Login details click Edit login details
- Then by using the drop down, change the user role to Engineer with diary