I need to transfer funds from myetherwallet to coinbase. I looked at https://infura.io/ and https://developers.coinbase.com/ and https://nethereum.readthedocs.io/en/latest/introduction/web3/#properties-methods-overview but so far no luck. Can you please point me to the resource for it.
It's unclear exactly what kind of advice you are looking for here. Do You need to do this personally, or are you writing software in C# to do this for others?
If you are doing it personally, MEW should have provided you with a mnemonic or private key that you can import into metamask. Once you've done that, simply copy your coinbase address into the metamask transaction UI and sending should be straightforward.
Otherwise, this should get you going in the right direction. (I havent used nethereum.)
2) ask the user for their intended destination address (don't use the coinbase api)
3) use web3.eth.sendTransaction to send funds using their desired signer. (MetaMask or a local node. This doesn't matter to you.)