Usually, when using a VSM, you will get the value of magnetisation of your sample in emu. Divide this value by the sample's mass and you get magnetisation in emu/g. Then, multiply M (emu/g) by sample density (g/cm3), and you get M in emu/cm3. Eventually, multiply M (emu/cm3) by 4*pi (=12.5664) and you will obtain magnetisation in gauss.