You should cut them into smaller pieces, with at least one "eye" per piece. Allow them to sit overnight and then plant them. If you've got some wood ashes from a fireplace or fire pit, rub the cut edges in the ashes after you cut them. I know you're not in the US, but there's a growing guide on this potato seller site: http://www.potatogarden.com/
Last year I tried potato in a container and I get three nice potatoes , so I did 2 container this week . Hope I have better results this year and I am using a mixture of homemade compost and potting mix.
I did bags that I purchased from Gardener's Supply (gardeners.com). There is a video on their website as well as printed instructions on how to do them in the bags. You could use that as a starting point. I plant 4 per their regular size bag and 8 in the jumbo. Do every year. Always have a good harvest, delicious, and no diseases or bugs. So easy. Enjoy!