N.B. The screenshots and descriptions are for the iPhone/iPad version.

Tasks are the regular and one-off jobs that need doing around the yard, such as mucking out, checking water troughs or preparing for a visit. They show in the diary on the days they are due.
What you see when you tap the Tasks icon depends on your role.
You see the list of tasks and can add and edit them. To let another user manage tasks too, go to Stables -> Users and enable 'Add Diary Notes & Tasks' for that person.
To add a task, tap 'Edit', then the '+' icon. Give it a name and, if you wish, a note, then choose the type, when it is due, and who should do it.
Daily - every day. Weekly - the days of the week you choose. Monthly - a monthly pattern such as the third Wednesday of the month (choose the week and the weekday). One off - a single date only, which appears in the diary on that day.
For daily, weekly and monthly tasks that are seasonal, you can limit them to particular months - turn 'Every month of the year' on for all year, or off to choose the months.
Use 'Allocated to' to give a task to a member of your team. They will see a count on their Tasks icon for the jobs assigned to them today, so everyone can see who is doing what.
When you tap the Tasks icon you see My Tasks Today, the list of jobs allocated to you for today. Tap a job to tick it off as done, and tap again if you need to undo it. The number on your Tasks icon counts down as you complete your jobs.