What are the special rules/laws if my relatives die and how I can help it?

ב"ה Shalom I wish all the best and may you know only of good tidings. The Jewish laws of mourning are multifaceted and detailed so I will refer to an excerpt to a newly published book in English. https://www.korenpub.com/media/productattachments/files/e/x/excerpt_from_hilkhot_avelut_small.pdf The Chevra Kaddisha who deal with Jewish burial, are fully informed on these matters and are able to assist in these matters. Immediately upon hearing bad tidings, there is a blessing to be said "Baruch… Dayan Haemet" , which means we call G-d the judge of truth and justice , and is he who rules over the entire world, it is He who gives life and it is He who takes it. It places the mourner in the proper perspective of life and death. I would also suggest reading the last Mishna in chapter 4 of Pirkei Avot= Chapters of the Fathers. There are also many books in English to prepare people to deal with their loss emotionally and spiritually according to the Torah tradition, among them is the boon "The Jewish way in Death and mourning." If you wish to be specific on a particular issue, I will try to be more helpful. All the best Shabbat Shalom and Chag Same'ach