How to go by bus from Hutong to Forbidden City & thereafter to Temple Of Heaven in Beijing?

For Hutong, do you mean the Houhai area?
If so, it is suggested to walk to the Denei Ganshuiqiao Station (德内甘水桥) where you can take the bus line 5 to reach Xihuamen Station and then walk to the Forbiddne City Station.

From the Forbidden City, you can walk to the Tiananmen East Station to take the bus line 2 to reach Tiantan West Gate Station. Then you can easily walk to the Temple of Heaven.