We read Eichah after praying Ma’ariv. Many Rishonim hold that a blessing is recited over the reading of Eichah, but many communities do not follow this practice. Moreover, many [poskim] maintain that even those who require a blessing agree that if Eichah is not written on parchment, like a Torah, no blessing is made. Nevertheless, few communities are careful to write the Scroll of Eichah on parchment. In practice, [all] Sefardim and many Ashkenazim, including all Chassidm, read Eichah without a blessing; while some Ashkenazim – especially those who follow the Vilna Gaon’s practices – read it from a kosher scroll written on parchment and recite a blessing.
It is customary to darken the Synagogue on the night of Tish’a B’Av, as it says, He has settled me in darkness (Eichah 3:6). The Midrash (Eichah Rabbah 1:1) similarly states that the Holy One, blessed be He, said to the ministering angels at the time of the churban, “What does a human king do when he is mourning?” They replied, “He extinguishes the lamps.” [God] said to them, “I will do the same,” as it says, The sun and moon became blackened (Yo’el 2:10).
Already at the beginning of the night, we turn off some of the lights in the Synagogue, and it is fitting to do the same at home. The main thing to be meticulous about is to dim the lights in preparation for the reading of Eichah, because that is when they used to blow out all the candles, except for the few that were needed for the reading (Sh.A. 559:3). Now that we use electric lights, some have a custom to turn off all the lights before the reading and produce the necessary light with candles alone. Others keep a few electric lights on.
The [Rabbinic] institution to read Eichah in public primarily related to [reading it] at night, as it says (Eichah 1:2), She weeps sorely in the night (Sh.A. and Rama 559:1-2). However, many people have a custom to read it again during the day, after the recitation of Kinot. In a place where the congregation does not read it [publically] during the day, it is proper for each individual to read it by himself (M.B. 559:2).