To make a task repeat or recur, you press on the task and choose the date and time to schedule it. Now you press, "Repeat never" and the menu with recurring options will appear. You can choose to repeat the task every day, Mon-Fri, Sat-Sun, week, month or year. You press on the option you like and you are good to go ready. The task will show up in your list on the schedule you made.
There are no other recurring options in the app and you can not customise them. However, if you would like a task to be repeated every Monday and Friday, you would have to make a task for both days and then make each of the tasks repeat weekly - one to repeat every Monday and one to repeat every Friday.
How to repeat a task on Swipes mobile app:
How to create a bi-weekly recurring task on Swipes mobile app (custom hack):
How to repeat a task on Swipes web app:
How to create a recurring a bi-weekly task on Swipes web app: