At any stoppage of play, with the referee's permission.
just go to game plan and substitute players
Play has to stop in order to bring on a substitute, whether it be a goalkeeper or an outfielder.
Yes, there is no problem with this.
about 5 or 6
Yes the goalkeeper is counted as the substitute in football.
Henry the 8th created soccer he used pigs bladders as the ball bladders are still used in soccer today sheffield as a substitute for cricket in the winter
Yes, it does count as a substitute. Replacing a player for any reason is counted as substituting in soccer.
No. Hence the term 'starting 11'
One. Go to center line, wait for a stoppage of play, and request permission of the referee to substitute.