Im also new to this. I have traded crypto´s before. I would transfer some BTC into my account at bitfinex, then exchange them into iota´s. From there you transfer them into the IOTA wallet, where you have full control and no private details has to be given. You only have to "remember" your personal seed.
For transfering BTC you could use coinbase, where you can buy BTC with your visa/credit card.
im not sure that this is what you are looking for?