Why sort of text would that be Op? Giving you an access to wallet for you ass the buyer to be sure you're buying a legitimate bitcoin like there had been adulterated developed bitcoin or what exactly is the need of the text?
Well, for the advice, as other members has refered you to the exchange, I think that's just where you can afford to buy such amount of bitcoin because it's a huge sum.
But instead of buy all at a time, I'd suggest you buy on DCAs so you can accumulate more to your assets. Don't you also think of diversifying?