When faced with adding events to your calendar, it’s useful to tap on the top left drop-down tab to choose how you want to view the current calendar (by day or month). Then you can simply long-press on a date or time to create/edit a New Event.
When you’re creating the event, it’s also useful to use the palette icon at the top right to choose a colour (to help differentiate it from others) or scroll to the recurring section to indicate if the event should be repeated; this will save time further down the line if the same event is needed again. After tapping Done from the main event interface, it will then appear on the calendar. If you need to re-edit it, you simply tap on the event and use the pencil icon at the top.