You can buy a theme deck at Wal Mart. Its just a deck that is already made. Also you can go to leagues to battle and trade. To find leagues go to the league finder at www.go-pokemon.com
you can also get a trainer kit wich has two small decks in them and have an extra pack two and its very efficient two so try that out two also if you know a league in your area you can go to and tell them your new and maybe someone will show how to build a deck and play so try it out^__^