Like with other cryptocurrencies, you will need a cryptocurrency wallet in order to use Dash. After receiving it, the user has a few standard options, such as sending it further, exchanging it for other currency, keeping it as investment or using it as a digital form of money.
Like other cryptocurrencies, the value of Dash relies solely on supply and demand. These factors can usually be linked to the popularity of the network itself. The more people use Dash, the demand is going to increase, further increasing the value.
Some exchanges offer a direct pairing between DASH and fiat currencies, allowing you to buy it directly with local currencies like USD and EUR. If that is not an option for you, you can purchase some BTC instead and convert it to DASH through a cryptocurrency exchange like Binance.
Apart from that, taking part in network operations such as mining and staking can result in additional profit. Understanding how nodes work and how to operate them is not straightforward and usually requires some form of education.