What necessary steps do I need to take to modify custody and establish child support from my original divorce settlement?

You will need to file an Order to Show Cause (court form) requesting a modification of custody and child support.  With your Order to Show Cause, you should file a declaration signed under penalty of perjury stating the facts supporting your request for modification of custody and child support.  The court will consider what is in the best interests of the child with regard to these issues.  The court will also consider changed circumstances such as a change in income regarding the amount of child support to be paid.

File your Order to Show Cause and supporting declaration with a proof of service with the court.  When the Order to Show Cause is filed, the court will schedule a hearing on these issues.  Serve a copy of your documents by mail on your ex.  The proof of service verifies the date of mailing.  You can either use a court form proof of service or you can write your own.  If you write your own proof of service, it just says that you are over eighteen and the attached documents were sent via first class mail unless stated otherwise to ___________ (name and address of your ex) on _________ (date).  You sign and date at the bottom.  The date you sign should be the same as the date of mailing and the same date you file your documents with the court.  Before filing your documents, check with the court clerk to see if any other documents are required, as the required documents may vary from state to state.