Hi! New girly here!

So I just started playing recently and I was wondering how can I make my own first deck, I was thinking about something like ✨gardevoar✨ But it seems legit HORRIBLE to obtain the credits to craft my cards. I've seem something about codes or something like that but no one seem to have one so idk what to expect from them

I would really like some advice or help ❣️❣️❣️