You will find the connector for the HRW under the carpet over the rear parcel shelf. However, unless fitted by the previous owner you will need to fit a switch and relay to operate the HRW. The switch and relay can be purchased of ebay.
Plenty of info on this on the web, we may even have a how to ourselves.
rayb's advice was correct I would just add you may need to adjust your window stops to get a good seal. After fitting the hard top I found it squeaked and made creaking noises for the first few days until it it settled down, so be warned.
The hard top is a very good addition for severe weather and the rear visibility is greatly improved.
You can remove the soft top before fitting the hard top if you are going to be using it for an extended period. I did this as I couldn't see the point in driving around with the dead weight of the soft top, which is heavier than the hard top by the way, so be carefull lifting it off if you do decide, it is a two man job.