You will have to file a petition to start the probate process.
A lot will depend on the size of the estate.
The heirs will all receive a copy of the will.
It is best to hire an attorney to assist and advise forthe process.
The answer given does not imply that an attorney-client relationship has been established and your best course of action is to have legal representation in this matter.
If you are not represented by a lawyer, you will typically begin probate by going to the Surrogate's Office of the county in which the decedent lived. In Essex County, the Surrogate's Office can be reached at 973-621-4900 . The beneficiaries in the Will should be sent a document called a "Notice of Probate" and offered or provided with a copy of the Will.
Here is a link to a blog article that outlines the process for you: http://info.njdivorceattorney.net/blog/bid/178792/New-Jersey-s-Probate-Process
This information is based upon the limited facts you presented. My advice Is based on New Jersey law and may be different if I find that the facts presented are different. Additionally, this answer does not contain any confidential information nor does it create any attorney/client relationship.