Hi Rutuja Mohod,
There is enough documentation in using restful service. Just incase you can find the documentation in the below link.
For how to consume the service
As you want to export file, You can probably make use of Community common module.
Community common is a market module which comes with some useful javaaction.
Among them, use FileToString java action.
This javaaction will convert the File to string and make use of this string and sent the data.
On the other side – make to use of StringToFile and convert your string to file.
Hope this helps!