Registration for a conference using authorize.net

Hi, I have a client that is going to put on a conference. They want me to set up online registration for them (which I've never done). There will be up to 1000 registrants. They need people to register & pay online (using authorize.net). Is this something that "Events+" can handle? I read, somewhere, that you can incorporate MarketPress to handle the payment portion? Can you point me in the right direction to show me how this would work? Trying to get out of having to purchase registration software. Thanks.