Here's how you can do that:
On the website: https://youtu.be/H1qo09F97LM
On the app:
Dashboard → The goal in which you want to set up the SIP → Invest → Start SIP → Fill up the amount, duration, risk level, etc. → Review and Confirm SIP.
Please note that you would be able to set up a SIP from your dashboard up to 1 day prior to the scheduled SIP start date. For example, if the scheduled SIP start date is January 7, you can set up the SIP till midnight on January 6.