99% of the time people use real (government-issued fiat) money to purchase Bitcoin (BTC). After that, you can use your BTC to buy other, less popular cryptocurrencies often referred to as altcoins.
You can use https://cryptoradar.co to find the best crypto prices on the market, but their system only supports a few cryptos and is too simple for my taste.
Instead, you can use https://localbitcoins.com which is much better in my humble opinion.
Obviously, when you buy BTC you will need a place to store your Bitcoins. The simplest way to store your crypto is to get https://jaxx.io wallet which is a multi-currency wallet available on mobile and desktop devices.
Jaxx has an integrated exchange service called Shapeshift, so you won't need to register on exchanges later if you want to buy, for example, Ethereum (ETH) later on.