Submit button functionality

Hi! I have added checkboxes to a page as a collection of data records named Tasks1. I can select each check box independently and they are recognized by the names data.Tasks1[0].Name, data.Tasks1[1].Name, etc. I would like my Submit button to: 1. Check that each checkbox has been selected, if not, throw a message that it’s a requirement. 2. If each checkbox has been selected for Day 1, then display Day 2 with the same Tasks, so on and so forth. 3. When signing in, pick up from the Days tasks where the users progress left off. Do I need to set a data variable or go in another direction? Can anyone assist me with this functionality? Thanks!