Hi Welcome!
I'm guessing you want to transfer MR (Amex points) to a certain hotel brand? You need to have a hotel rewards account set up. If you want to transfer points to Marriott, you need a Marriott rewards account.
It's super simple to do online.
You login to Amex and click Explore Rewards
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From there you just select Transfer points
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Regarding the buying points, sometimes hotel brands will have sales. It sounds like he bought Hilton points during one of their sales. You'll have to keep an eye out for those sales.
Sometimes Amex will have a transfer bonus, right now they are having a 20% transfer bonus to Marriott. You'll get 1,200 Marriott points for 1,000 Amex points.
Sometimes the transfer is instant, some programs can take 24-48 hours.
Does this help? Feel free to PM me if you need more help.