It doesn't matter how much you have. Someone correct me if i am wrong but "freebasing" involves using amonia and as i am not familiar with this i won't give any bad advice.
Making crack, which for all intents and purposes is essentially the same as freebase albeit lower quality however safer to make; involves baking soda which i am guessing is what you are talking about.
Take your coke, any amount will do a gram is more than enough, put it in a spoon, shot glass, or ideally a glass test tube - and add slightly less baking soda than you have coke. Make sure its baking soda not baking powder. Add enough water to moisten it all, stir it, then heat it up until it is at a slight boil for 10-20 seconds then stop. If there is still some liquid heat it up some more but don't boil it for too long at once. When there doesn't seem to be much liquid it all then let it cool for a bit until it hardens then scrape it out, chisel it out, whatever and enjoy.
I know this method is not "perfect" but it works, and pretty well from my experience. Depending on the quality of coke add slightly more baking soda and water and re cook it to make sure you don't waste any, a little extra baking soda won't hurt.
Also i am pretty certain there is a crack cooking megathread, im sure the baseheads in there will help you out.