I want to connect Ganache to Ropsten such that i can see Ropsten's ledger with Ganache. Is this possible? if yes, what settings do I need to do on Ganache?
Ganache is a local blockchain that you run in your own computer, whereas
Ropsten is a public blockchain. Therefore, both are different blockchains, meaning that you connect either to one or another.
You can use Metamask, for instance, and easily change to your local blockchain (Ganache) or a public testnet (Ropsten, Rinkeby, Kovan...).
To set up Ganache with Metamask, go to settings->networks->Add network, and there you can put the values from your Ganache configuration (URL, port, chainId).
As pointed out by @goodvibration, you could actually fork Ropsten network, run it locally (so you would be the only node), and then connect Ganache to this network. This might help you: