This can be done on the Healthrota website or in the app.
The website is much easier.
On the website go to "File" -> "Rotas" -> "Critical Care Consultant Rota"
If not already seeing people's names in column go to "View" -> "View Members Grid"
Find your name.
Highlight the dates you want and just type the leave or availability type below.
Annual / study / professional leave
No work / short day only / night only / no night shift / other work / anaesthesia