At Oxford University, students added the suffix "er" to the end of words that they shortened. This was a local version of slang. For example, "Rugger" stood for Rugby.
One day a student by the name of Charles Brown was asked to play rugger, but he replied with "soccer" instead. He shortened association, which is what soccer(football) was known as then, and added "er" to the end.
This Charles Brown did end up playing soccer for the international soccer team in England. Shortly after the English football league was formed, including the following teams
Accrington
Aston Villa
Blackburn Rovers
Bolton Wanderers
Burnley
Derby County
Everton
Notts County
Preston North End
Stoke City
West Bromwich Albion
Wolverhampton Wanderers
And in September 1888 Jack Gordon scored the first ever goal in this new league!
Although the question "who invented soccer" can’t be answered, I hope this article did give you a good background of the sport!
Find more info on equipment for soccer youth at this page.