Lol ive been through more than 73 tutorials, a book, and other websites and you saying i have to learn the basics.. This is probably one of those things that werent taught so.. and this has to do with sfml. the sf::RenderWindow() parameters..
No, it really doesn't. If you managed to read that many tutorials and they never covered defining functions, let alone classes, you really need to pick different tutorials.
void Display(sf::RenderWindow(sf::VideoMode(int,int,int), string);
That line for example is proof positive that you don't really understand the syntax of defining a member function. You are combining aspects of a function declaration, implementation and call all in one. I can't even decipher back to what you were even trying to do.
Coincidentally, if you want to pass a RenderWindow into a method Display you would define it in the .h as:
void Display(sf::RenderWindow&)
Then in the .cpp file, you would declare it as:
void Player::Display(sf::RenderWindow & renderWindow)
{
}
Note the lack of semi colon. Another mistake in your example ( the semi colon at the end of the implementation ) is telling you need to work a bit more on the basics.
But hey, whatever, good luck.