I'm doing isotope homework and I need the find the number of protons, neutrons, and electrons

first one is chromium-58 and chromium-63

Chromium is element #24 on the periodic table. The 58 and 63 indicate the mass of the atom in amu. Protons and neutrons both weigh 1 amu so chromium-58 weighs 58 amu. Since changing the amount of protons would change the element, they must remain constant. Neutrons however can vary so the difference between 24 and 58 (and 63) is made up of neutrons entirely. Assuming a neutral atom, all isotopes will have 24 electrons, which are essentially weightless.