First go to Coinbase.
You can connect your credit/debit card and/or bank account, and off you go.
Now you can buy, sell, send, and receive Bitcoin, Ethereum and Litecoin. If you want to additionally participate in ICOs that are offering Ethereum ERC-20 tokens (as most currently do) you’ll need to transfer some Ethereum to a non-Coinbase Ethereum wallet (Coinbase is actually a service and not a fully user-controllable wallet). This will then allow you to send some Ethereum to various ICO contracts and get the corresponding new and different tokens sent back to your Ethereum wallet. To do this, go to:
MyEtherWallet.com · Your Key to Ethereum
MyEtherWallet (MEW) is a free, open-source, client-side interface for generating Ethereum wallets & more. Interact with…
Follow the instructions to create a new wallet and keep good and secure track of your password, wallet address and, most importantly, your wallet’s private key.
The wallet address is like your bank account number and you will need to share it with others from time to time to receive funds in that wallet. The private key is like your bank account password, finger print, retinal scan, social security number and drivers license all wrapped up into one when it comes to accessing just that one wallet. Any one with the private key and public address for one of your wallets is you and can do whatever they want with the funds in that wallet. You can set up wallets all day long — they are simply addresses. Just don’t give away or lose your private key, especially if the corresponding wallet has a lot of value in it.
Now you are all set to buy, sell, send, and receive Bitcoin, Ethereum, and LiteCoin, and also participate in Ethereum-based ICOs.
For more detail on the ICO participation process see this article by Stewart Dennis at BitBounce, starting at point 14, and for more information about Ethereum transactions, gas, and sub-units of ether, please see this article.
Finally, for more information on managing various wallets and converting between various cryptos with the JAX software wallet, see this article.