you'll have to talk to the people, they will then instruct you in which direction and building to go to. If you don't talk and just go, the kid will not be there. talking to them is like activating the next activity. the first person to talk to i think is the one standing right at the entrance close to the intersection. then just follow the instruction and talk to the other person in those location until you reach the training ground. if you go straight to training ground, the kid will not be there.
What happens after I follow Gaara into the Gaara pursuit? When I defeat him and the possum, credits roll. Is the game really over? and Why can't Sasuke use other jutsus than lions barrage and the other one?
The game basically over. all you can do afterward is unlock stuff. and i heard you can play in a dojo to try out your new unlocked techniques. You can even unlock jiraya-sama or ero-senin as one of you. and a bunch of stuff. well is not worth it. nothing to do afterward. just move on to another game.