Remember the basic rules for naming ionic compounds. You need to either memorize them or use a table for metal cations that never change charge, and nonmetal anions that keep the same charge.
Understand when the ions join to form a compound the overall charge is neutral.
Name binary ionic compounds that contain a metal that form only one type of cation by the formula: first, the name of the metal cation, and second, the base name of the nonmetal anion, + ide. Like CaO for calcium oxide, or KCl for potassium chloride.
Apply the rules above with a different twist for binary ionic compounds that contain a metal but form more than one kind of cation. Here you will start with 1) the name of the metal cation 2) the charge of the metal cation in roman numerals in parentheses 3) the base name of the nonmetal anion + ide.
Know the overall charge of the binary ionic compound is neutral. Infer the charge of the metal in the compounds by the charge on the nonmetal. For instance, if there are three atoms of the bromide (nonmetal) element with a 1- charge for each, the metal cation, say chromium will have a 3+ charge. The compound formula is CrBr(3), and in words: chromium(III) bromide. Close up any space between the metal name and the roman numeral in parentheses.