how to modify/update database row using wcf http json

how to modify/update database row using wcf http json

I am looking for way to update the database record. I am using android
client to take input from user. Android client is communicating with sql
database through wcf json written in c#.
I googled and also search through stackoverflow, finally come to know that
I can use http PUT to update the record. I tried to implement the http PUT
method in my android client and c#. Its working fine in c# (checked by
fiddler).
I want to use json http method not xml. hence searched and didn't find any
good working example.
Please help how can I implement Http Put json method in android.