First you will need to attain an undergraduate and master's degree, because careers in child psychology typically require doctoral degrees. Your undergraduate degree can be in anything, not specifically psychology, but any coursework pertaining to child psychology can only be helpful. Training includes the basics of psychology pertaining to child development, family systems and learning processes. Some coursework in child psychology programs may include the academic study of pharmacology. Most programs require students to perform research on an issue in the field, like economic or biological factors that affect child development. In addition to their studies, students are generally required to complete a one year internship. During the internship, students may monitor, observe and assess children for behavioral or other disorders. Other duties may include administering personality tests and researching the effects of medical drug treatments. Good luck!
To become a child psychologist you need to do the following in terms of education.
First, you need an undergraduate degree. You do not need to major in psychology, but it does make sense to do so. Most psychology programs are not too demanding in terms of course work. So, you will be able to take many other courses.
Second, you will need a PhD in child psychology. This requires typically five years of study. It is really a long haul. So, you need to make sure that you want to do it.
There are also master's degrees in psychology, which take two to three years to complete, but it is best to get a PhD.