I have put a brief description of the soccer positions on a team in the Basic Guide to the Game if you are a beginner and would just like a very basic explanation.
This page will go deeper with the soccer positions. I am going to explain about the different talents and fundamentals you will want to be strongest in for each position.
This page may give you a new way to think about how you play your position. Or maybe you know your position well and are looking into other soccer positions. This page will help with that as well.
There are many ways to set up a team, but I am going to give you the most common one which I have always found to be most effective.
The basic structure of the offensive set up (when you start with the kick off) is shown in the photo below.
There are two strikers (red), four midfielders (yellow), four defenders (blue), and a goal keeper (purple).
The idea on the offense is to be attacking in two lines of four players. If your offensive players are good at working together, this set up is hard to fight off.
The basic structure of a defensive set up (when the opposing team starts with the ball) is shown below.
The number of players in each position is the same, so the players who are both offensive and defensive (the midfielders and fullbacks) need to be able to adjust between positions quickly.
Like the offensive set up, this makes the main structure two lines of four. Except this time it is just on the defensive side if the field.
The two lines of four is a strong set up. If a soccer team can get this structure down well, then it will automatically step up the level of play.
When playing soccer, the skills you develop and which fundamentals you are strongest in will depend a lot upon which soccer position you either like to play or just get put at a lot.
For example: a soccer position such as the goal keeper would require a whole different set of skills than any other position. It would require you to learn more with your hands, drop kicks, and free kicks.
Also a defensive player on the soccer team would need more tackling and long passing skills than a more offensive player who, in turn, would need more dribbling and shooting skills (though passing is still incredibly important).
I have learned that it is best that, no matter what position you normally play, to learn as many skills and positions as you can (though you still want to be strong in the ones pertaining to your position).
Some of the main reasons for this are:
While this structure is powerful, I do not want you to think it is set in stone.
In a soccer game, many times improvisation is needed. Sometimes a player needs to leave his position and another player has to cover the hole that is left behind.
You can also move more players to offense or defense or make other changes as you see fit for your team.
Many teams will drop
I'm just trying to say there is no mandatory set up, but this is a very strong one.