A few points, hopefully may help you.
First of all you need telstra bigpond internet to access the foxtel.
You also need your internet switched on to access the foxtel.
If it is wireless make sure the signal is strong enough. If not you may need to buy something to make the wireless signal stronger (sorry, I'm not very technical and don't know what this "thing" is called).
You also need to have some credit left on your internet access for the month for the foxtel to work. If you are on the slowed service for going over your limit the foxtel will not work.
There is also a forum on the bigpond site where you can post your query, and other bigpond users can give you an answer. You can also search the archives.
I don't have telstra bigpond foxtel myself, so I can only give you these very limited suggestions (I do have a t-box though). If I think of something else I'll come back and post it.