Previously, he was an abandoned kitten, and now requires attention. It often happens that the animals be on the street accident (run in heat, fall out of Windows, etc.). So first it is better to search for the former owner.
This can be done with the help of popular online sites. Also you can print out and putting up flyers in the area where the animal was found. If the search of the former owner has not given the results?
In this case, as stated in a famous book, you are responsible for those who tamed. In other words, now you have to do everything in order to find a home and a potential host for the found animal.