Kittens that little can't defecate on their own yet - Mamacat helps them with that process by licking their anus until they go. As the surrogate Mamacat, that is now your job - but you can use a piece of soft warm moist cotton - not your tongue so don't worry:-). Occasionally, with little ones that young, it may still be difficult to get them to go. Contact your vet - they may need to have an enema and the vet should do that - until such times as he shows you how to do it. Don't give them any type of laxative or anything made for humans - that could prove fatal.
If you can find an adoptive mothercat who can nurse them, that would be the absolute best! If your friend's cat is still able to provide milk, you can try and see if she will accept them. If there is a way to make the kittens smell like she does, she will be more likely to accept them. I am not sure if Hissy's vanilla trick is the best for this or not - I am sure she will post if it is - but if you can get a towel of something that the mother cat has been lying on or using and has her scent on it to rub over the kittens before they are introduced to her, that might work. I have had several adult cats willingly take on some of the mothering duties of new kittens even though they could't nurse, and in barns and stables, mother cats will often share nursing responsibilities of each other's kittens, so it is certainly feasible.
Good luck. The other important thing to remember with them at this age is it is imperative that they stay warm - warmer than you are comfortable at - so often some additional heat source in a small box, padded to protect them from too much heat, is a requirement.