pass parameter values to dataflow from pipeline

hi,

at the end of the pipeline, a dataflow is being executed.

at present I have hardcoded the parameter values in the dataflow to get the dataflow to work.

now I have started creating parameters in the dataflow, i.e. filename, currentdate

so I added parameters to the dataflow by right click in the dataflow and add parameters...

questions:

1- how do I pass these parameter values from pipeline to dataflow?
 2- how can the dataflow read the passed in parameter values?

thank you