The syntax error you are receiving is because of the semi-colon at the end of your function declaration which causes the spriteBatch variable on the next line to be out of scope.
public void Draw(SpriteBatch spriteBatch);
<= This colon.
spriteBatch.Draw(text, position, Color.White);
<= Out of scope because of the colon on the previous line ends the function scope.
Change the code to this and things will work.
public void Draw(SpriteBatch spriteBatch)
spriteBatch.Draw(tex, position, Color.White);