My Beginning in Splinterlands

I started to play splinterlands last week, I’m watching on youtube about NFT games and splinterlands caught my attention cause this game can give me income, but when I played it I notice that I haven’t earn DEC, cause all I know is the game is free to play to earn! but then I started to fund my account and I am happy to play this game.
Since I want to expend my time playing but earning.