Parsing and Executing Command Object in WebService

Good day all,
In My Implentation, i want to pass command object to a web method to execute stored procedures and return a dataset
like
[webmethod]
public DataSet spExecuteDs(Sqlcomand Objcmd)
{
ds ....
// code to consume here
retun ds
}
 but it seems it not working.
i need a better way to handle this
...