if you have test and it is dosed at 250mgs per ml and you have a 10 ml bottle then you have 10 mls or cc's of 250 mgs of test.
if you want 500mgs of test then that would be 2ml's or 2cc's of fluid.
needles are marked in ml's so people normally use ml's instead of cc's
the important thing is to get your dose correct. mgs always is related to dose of the product not the amount of fluid . the amount of fluid would be stated as cc or ml ..
next week you'll learn how to get 500iu out of a 5,000iu bottle using 5mls of water!