How does buy price of Mutual Bond Fund rise if not without buyers buying in


I’m new to bond investments and recently bought 50k worth into a long term mutual bond fund minimum of 3+ year recommended hold time, which consists of indexed bonds given out or backed by the goverment. What I don’t understand is the “dividends” or intrests are reinvested, does the buy/sell price rise according to the amount that they reinvest? What makes the buy in price rise if not without other buyers like me buying in?