The French numbers spelling are like the same composition as the English numbers, but there are some rules:
examples :
for the twelve first numbers, it is just one word: one-un, two-deux, three-trots, four-quatre, five-cine, six-six, seven-sept, eight-huit, nine-neuf and ten-dix, eleven-onze, twelve-douze.
Thirteen to nineteen, in English you add -teen, in French it is -ze, like treize, quatorze, quinze, seize. BUT for seventeen, eighteen and nineteen, in French it is NOT THE SAME! it is like ten+seven, ten+eight, ten+nine, so it is dix-sept, dix-huit, dix-neuf.
After these numbers, it is the same in English or in french, it is twenty+one, vingt+(et)+un, vingt-deux....
BUT in French for seventy and ninety, it is sixty+ten and eighty+ten, such as Soixante-dix and quatre-vingt dix. and after you take the soixante to the quatre vingt and you add the from eleven to nineteen.
Hope this help, and I hope you understand me!