How to pass Arguments to the activity generated by New Services

Hi ,
I just created a Activity generated by New Services by creating a library the activity is calling a SOAP method and the method requires 2 parameters , the first parameter contains DataSet and second one is String , how can i send the Params to that activity
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and what i have to do after this , i need to drag that activity in a Sequence like this
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and call that activity and then create a package or i just simply create a package without this .
And i am getting this error


how can i add headers , headers option needs a dictionary how can i add headers for windows authentication , i checked the "Windows Authentication option as true , but still getting this error.

Please Help

Thanks