How to earn my first bitcoin in baby steps?
HOW TO BUY BITCOINS

1) From exchanges. Exchanges are many based on countries. UNOCOIN is a popular one for India. Alternatively, if your nationality is different from what I presumed, you can have a look at this site for many exchanges and wallets: COINDESK. You can create a bitcoin wallet here: BLOCKCHAIN

2) Have a look at this link for more detailed explanation: How do you obtain bitcoins?

WHERE CAN I SPEND THEM

You can spend them on websites/services which ACCEPT bitcoins as a mode of payment just like Paypal, Credit Card or Debit Card.