I have bought a laptop with a wi-fi card.

Right now I need to use it at Heathrow and the only wi-fi networks
detected are by: Wanadoo, BTVoyager, and Netgear.

These are all secure and require a password to use.

I'm new to this. How do I subscribe to start using these?

I'd prefer to use Wanadoo simply because it appears to be the strongest
signal out of the three.

Many thanks - CJB.