You can achieve the behavior you are looking for by creating several sections in your document - title page, table of contents, etc. Then you can make sure the sections you want paged have theirs FirstPageNumber
For example, you can create two sections - put the intro information in the first one and the content in the second section. Then you should set the mentioned property as follows:
secondSection.FirstPageNumber = 1;
Now when you insert a page field in the second section, it will start from 1.
I hope this information is helpful! Please, do not hesitate to get back to us if you need further assistance.
All the best,