Welcome back, mimififi... you were missed...
Here in the U.S. we try to plant potatoes in early April, but there's no reason you can't still plant. Be sure the soil is well worked to a depth of at least 10 inches, 12 inches is even better. If it's heavy soil, work in some rotted manure or even sand. Plant about 8 to 10 inches apart about 3 or 4 inches deep. Water well, but not so as to have standing water. Water only about once per week.
Here's something I've tried and had good luck with. Obtain a plastic garbage can... at least 25 to 30 gallons in size. Drill or cut some holes in the bottom. Place about 8 inches of dirt and plant maybe 6 potato eyes around the circumference. Water a little. They'll sprout fairly quickly. When they're up about 5 or 6 inches, put in some more dirt almost but not quite covering them. Continue to do this as they grow. You'll wind up with it about full of dirt. Leave it alone when the potato growth is within a few inches of the top and let the tops die back as usual. Last year we harvested nearly 50 pounds of potatos out of one barrel. Any barrel can be used, but if you don't have one readily available the garbage can works very well...
By the way, use a superphosphate (0-20-0) or bonemeal (2-11-0) when you first plant them for quick root development (but don't let it come in contact with the seed potatoes at planting) then use a light hand and apply a good balanced commercial fertilizer, such as 5-10-10 later in the season... Good luck!