Same like you're burping your baby when he/she is awake. Put baby on your lap, hold the neck and pat the back or easier put your baby on your shoulder, make sure the stomach is on your shoulder and pat. Baby will burp faster this way. This is also how the ang mos do. I learnt it from Instagram 🤭
I just hold their neck let them sleep and burp them.
https://sg.theasianparent.com/burping-your-baby