Hera can be picky to talk to. She may not respond right away, but there will be signs that She is listening.
I would first read up on those two Goddesses and see what They are like, what Their symbols are, what makes them angry and what doesn't, just so you have a good idea of what you want to do.
An offering, and then asking a "favor" (in this case, you would want to talk to Them) is how I would suggest you go about doing this.
Here are some links:
I hope this helps! Best of luck!