This is going to be pretty simple, since Fredward Benson, Freddie to all his friends, is a pretty normal dude.
He comes from the Nickelodeon show iCarly (and hails from the same reality/timeline as fellow iCarly character
hurtingzeebo), a wonderful world of wacky consequences, young teens flourishing against adversity, and fat cakes. It's very much a heightened version of our own world, only with certain pop culture icons parodied (Apple becomes Pear, Disney becomes Dingo, Star Wars becomes Galaxy Wars). Oh, and there have been non-imaginary angels and kids who can do real magic (and no one freaks out about this).
That said, Freddie is a normal kid. His peculiarities come mostly from his upbringing, because his mom was super protective. And despite her near-constant causing of embarrassment for Freddie, he is a mama's boy. And even far away from his mother, he'll still fall prey to her efforts to make sure he gets tick baths and shampoos twice each shower.
Also, he has a tracking chip in his head, also thanks to the aforementioned mother. Anyone who could somehow sense this is more than welcome to.
He also has a tendency to say phrases in Spanish at times. Fan-theory is that it is because of his tracking chip (it is Venezuelan), but this is not canon and will remain a mystery, at least until canon says something.
But otherwise, Freddie is a geek, and constant victim to Sam's pranks and teasing. He's a good and loyal friend, however, and will probably make friends with just about anyone who is even slightly nice.
As for the iCarly webshow,
Sam's player has a good briefing as to what is going on there.
So... questions, comments? Offers of pie?