How do I "complete" a task?

The only problem I seem to be having is how to complete a task. I dont want to skip it, or delete it, etc. I would like to have it "checkmarked" as completed so that I can track that I have done the task....Otherwise, I love the ease of use and different options available. I have purchased the app. :-)

Karen100680 about Reminder with Voice Reminders, v3.5