What are the indications that it's broken?

If it's only a cut, then with one person holding him, have another person
pour hydrogen peroxide into the cut. Thoroughly flush the cut. Then pack
triple-antibiotic ointment (a.k.a. Neosporin, but available generically for
less money) into the cut. Wrap the tail with the cut on it with gauze
bandage and then First Aid adhesive tape.

The cat might benefit from an oral anti-biotic. The above won't ensure there
is no infection.

If it's clearly broken, you could try googling to see how to set it.
Otherwise, keep checking back here; call your local animal shelter; check
with a local vet to see if he/she will let you pay on installment.

"Elaine Lilly via CatKB.com" wrote
my daughters 3 month old kitten has a cut on his tail and I dont know how
it got there and I think it might be broken. I have no money to take him
to the vet because my mom just died and I had to pay for
everything...please can someone help me on what I can do for him hes
playing and eating but when I try to look at the tail he runs from me and
I
cant get a good look at it please help its my daughters kitten that she
got
exactilly 2 or 3 weeks after my mom died.