If you have been assigned an action you will be able to see this on your dashboard under My Tasks. Your dashboard will show you all outstanding tasks, not just Actions.
You can filter on the different types of tasks assigned to you using the filter icon on the top right hand side of the page
To filter on just your actions, from within the filter panel, select the relevant action Type. You can also further filter on other fields such as Priority and Status.
Your dashboard tasks list will update accordingly to show only the filtered results..
It is good practice to add regular updates to actions so that there is a clear audit trail of activity.
To view and update any of your actions, simply click into the action from this list.