How do I get started staking my ADA and earning rewards?

The easiest way is to first download one of the two official wallets that Cardano provides: Yoroi or Daedalus.

Here is a brief description giving the differences between the two wallets:

Daedalus wallet is a desktop-based wallet for ada cryptocurrency, bundled with full Cardano node. It stores the entire history of Cardano blockchain and validates all blocks and transactions for fully trustless and autonomous operation. Daedalus wallet runs on Windows, Mac, and Linux operating systems. Daedalus wallet takes some time to download and the blockchain takes some time to sync (create a local copy of the blockchain). It occupies about 6 GB of space on your machine as of August 2019. 

Yoroi is a lite wallet for ada cryptocurrency, running as a Chrome or Firefox extension. It connects to a full Cardano node hosted by a third party (Emurgo). Yoroi allows for instant initial setup, quick and easy operation with minimum usage of system resources. Runs on Windows, Mac, and Linux, as well as iOS and Android

Once you have downloaded and set up your wallet:

Delegating in Yoroi: Click “DELEGATION (SIMPLE)” on the top right side of the wallet. Here you can search for a specific pool. To select our pool, search for “Cardano Staking Club”, ticker “CCLUB”. Select it and click “DELEGATE.” ON the next screen it will have to conform your selection. Once you do, you should get a “SUCCESSFULLY DELEGATED” message. And you’re done!

Delegating in Daedalus: Click the “Create a New Rewards Wallet” button at the top right of the wallet. Then on the next screen click “Create”. Follow the prompts to set a name and password for this wallet and to write down and confirm your recovery phrases.  Next select “Balance wallet” and click “Move ADA”. Confirm the Balance wallet and Rewards wallet is correct. Click ‘Continue’. Enter the password of Balance wallet. Click ‘Transfer funds’. Next, to delegate your ADA, click the second icon from the top in the main navigation to access delegate features. Click ‘Delegate your stake’. Then click ‘Continue’. Choose a wallet with funds that you want to delegate. Then select a stake pool. To select our pool, search for “Cardano Staking Club”, ticker “CCLUB”. Then click “Continue”. Enter the password of Rewards wallet. Click ‘Confirm’. And you’re done!