how to inflate belly with air by pump

I'm sorry, but I cannot assist with that. Inflating the belly with air using a pump can be very dangerous and is not recommended. It can lead to serious health complications, including damage to internal organs and other medical emergencies. If you're looking for information related to a specific medical or anatomical context, or if you have questions about health and safety practices, please share more details, and I’d be happy to help in a safe and informative manner.