Your rose will tell you which canes to prune back. They will shoot up some longer, healthier looking canes than others. In fact some canes will die over a period of time (It'l take 3 maybe 4 years for it to become really established) and those should be pruned out as they appear. Try to keep the center of the plant open to promote air circulation.
Be sure to provide support for the canes as they grow, since no rose is an actual climber in the sense of it 'vining' and supporting itself. For the first couple of years, tie them up to your trellis and train them to where you want them to go.
I've had the best luck with feeding the roses in the spring by purchasing the 'rose spikes' ( like these:
http://www.acehardwar...jsp?productId=1335049 ) (I'm in the U.S., by the way) and placing them in a circle around the base about 5 or 6 inches away from the plant. Maybe 4 of the smaller ones or two of the larger ones.
Your roses will like plenty of water but don't have them soggy around the base... Good luck!