How to read recorded transactions on the blockchain and track addresses?

How to interpret transactions recorded on the blockchain? Let's say I know the wallet address and want to track it, for example on Etherscan. How to recognize if something has been purchased? What and where was it sent - exchange or private wallet - how to distinguish it? What was a transaction fee, and what was not? I have absolutely no idea about it. Alternatively, if someone could point me where to look for such information? Screenshots with descriptions would be helpful. Thanks in advance!