The 24-year-old from the US city of Milwaukee, Wisconsin, says he is excited to be given the opportunity to be the first American to play the sport at the highest level, and that the challenge of the unusual lured him to the game.
"I'm all about doing something new and unique - for Americans, not too many people know about Australian football, unfortunately," McNamara says.
"To be the first to actually do it, I think that's pretty cool in my book - my goal at the end of the day, besides just kicking some tail out on the field, is to bring the sport over to America.
"Everybody that gets educated about it, and watches it on TV or through YouTube, they're like 'Man, this is the coolest sport in the world'.
"And I think so too, obviously."
McNamara stands 204cm and weighs 104kg, and the Magpies are hoping he will become a ruckman or a key forward.
He was speaking on the first day of the AFL Player Induction Camp in Melbourne on Monday.
The Pies gave McNamara a two-year international rookie contract after he introduced himself to them via a YouTube clip, and while he says the camp is similar to ones run by the major sporting codes in the US, he has a warning for the youngsters entering the system for the first time.
"I think it's great - what they're doing is a lot like what they do in the States for all the other big-time sports," he says.
"It puts it in perspective for the young kids who really just think 'Well this is cool, like I deserve this'.
"Well, it's like no, it's a privilege, it's an honour - you're representing your family and your friends, and now you're representing a club and a business.
"This is really good; I think it's great for the kids."
The camp finishes on Tuesday and has 122 inductees attending, which gives some idea of the massive turnover each year in player ranks.
Steve Alessio, the AFL Players Association's general manager of player development, says that despite a spate of recent off-field dramas for the league, the message about behaviour and responsibility is getting through.
"It is disappointing when that happens, but we're confident that the way we're going about it is the right one," he says.
"I think if you look over the last few years, the amount of knowledge the guys have taken in and have put into place in their own careers, I think they'll benefit from it.
"These guys come from diverse backgrounds and learning levels, so it's a constant thing we work on.
"Today at the induction camp is the first port of call of a career-long education and development program with these players."
