Reduce weight

Sir,

I am 46 years old.  My weight is 75 kg. Three months back, I had undergone incisional hernia operation.  I have BP and taking medicines for it.  When I had taken scan, it shows that My liver is fatty.  My chest side and stomach is slightly bulgy.  I want to reduce my weight both in stomach and chest.  How to reduce fat in these portions.  How to reduce my weight.  Daily    I am walking for 30 minutes in the tread mill.  No other exercise due to hernia operation.  What is the dos and donts to follow after surgery.  Can I do yoga and other exercises?  if so what are they?  Please help me to reduce my fat and weight.  Thank you.  Expecting early reply.