What website did you use to purchase your first amount of BTC?

I'm sorry if this post is not something that follows the "rules", but this is something that has been bothering me for a while.

I really want to get into trading altcoin and I know the only way to do that for me is to buy some BTC so that I can trade it to STEEM or another coin. The problem is, I don't have any idea which website to use to purchase my first BTC with a debit card. Coinbase is the only one that I'm sure will do what I want, but is the website trustworthy enough to give my ID? If someone could please just take a second to explain this one tiny step to me I could invest in Steemit!

TL;DR How do I purchase BTC with a credit/Debit card to trade into steem and other altcoin? Can I trust coinbase?