Oh Ann , what a difficult situation ....! Of course , a vet's advise would be the best , but as you cannot afford it , I would try that shampoo . But , have you any idea of that kitten's age ? Some products are NOT to be used on very young cats ; my vet used a spray for my youngest kitten Inka . I have her since one week ; she was found too and had fleas as well . They all have dissapeared now !
Wash your kitten very carefully (in luke-warm water) , and be sure to do this in a warm area ; be sure also that NONE of the shampoo gets in her eyes !!
Also get her dry as good and as soon as possible !
Good luck Ann , youare so sweet to take care of that lil one !
Let me know how it goes , okay ?

ps. you can read all about the changes in my fur-family on my brandnew website !