How can you catch a a small size turtle?

i live like right behind a lake in central FL and 14 years old and i want to catch a turtle i have before i dont really care if its a snapper (because in my lake most of them are) i just want to catch like a 3" turtle or a very little baby one and raise it please help me ( and how can you not get salmonela from having one;like is there any precautions i need to take and it going to be in a tank outside) again PLEASE HELP ME!!!!!!!!