The school can help with an IEP, call the school, tell them you want an evaluation done. As Christine says below, they will do one and then if the child qualifies they will have a meeting about what he needs to be successful.
However, the school will not diagnose ADHD. It's not really in their power. He needs individual care.......a doctor and counselor to help treat the ADHD. To help him learn how to overcome his weaknesses (counselor) and to make it easier for him to do so he needs medication (psychiatrist). You can just go to a psychiatrist, they will give you a rough diagnosis and set you up with a counselor to work with, but if you TRULY want to know FOR SURE what's going on and if it's ADHD or not, you have to have him tested by a psychologist. They are the official "experts" that diagnose. Then if he gets the diagnosis, the psychiatrist monitors and prescribes medication and the counselor helps him learn how to function better in daily life.
Medication can sound scary for a young child, but honestly.....it is needed. There is a chemical/neurological problem. It will be much much better treated if the child receives medication to help control the symptoms. Then with time and working with a counselor they can learn how to control it somewhat themselves. Some people can go off meds, some continue to need it. Once you get a child on the meds, treatment and therapy with a counselor is much more effective because you have the symptoms under control.
For some insurance you need referrals for psychological testing, so first step would probably be to call her insurance company to get a list of psychologists in her network. Then the school can be a good resource as far as who is a good psychologist and/or psychiatrist to see. They see alot of evaluations come in and have worked with alot of these professionals. Our district has a nurse that specializes in working on IEPs and I have found her knowledge to be invaluable.
For sure, go to the school for help with school, but privately he needs help just to make him a successful person in life overall as well. Trying to work only with the school can be like pulling teeth cause the last thing they want to do is spend money. They have to abide by the law and provide a free and appropriate education for any child with a disability, but that doesn't mean they have to help them become all that they can be. It means they have to make the effort to help him be successful in school with whatever tools they have at their disposal. But individual treatment beyond school is what is going to have long term effects.
A great place to go for info http://www.chadd.org/