It's super simple!
Supporters can now choose to set up a regular donation to your cause, meaning that you'll automatically receive a donation from them every 30 days from when they've set it up.
On your project page, make sure to let your supporters know that they can now donate to your cause on a monthly basis. State clearly what the funds will be used for going forward, so your supporters know exactly what they're funding.
You can also direct them to this supporter guide, if they want more information.