You will only manage your own player and depending on your actions (passes, assists, goals...), other teams could be interested in your services. That way, you will gain fame and money, which will serve to give you an idea of how far the player you created can get.
Furthermore, the gameplay is very entertaining. It reminds of classics such as Sensible Soccer or Italy 90. Even the most veteran player of this type of football games will enjoy like a child with each and every one of the matches.
New Star Soccer 3 is a very pleasant mix of manager and football simulator that can give you hours and hours of fun if you like both genres.
You can only play 10 matches of the League.