Don't know what brand/model pressure "cooker" you got (you didn't share that info with us) - and it doesn't help not knowing where you live (you didn't include any location information in your user profile - not even what country you live in) but if you are in the US or Canada and if it is only advertised on the box as being a presure COOKER - I wouldn't try to use it for canning. You can pressure cook in a pressure CANNER ... so some are marked as pressure COOKER/CANNERs or CANNER/COOKERs.
In reference to the pressure cookers sold here in the US,McNerd was right about the part, "Cookers have a thinner construction and designed to heat up and cool down quickly. Canners on the other hand need a steady temperature and cool down slowly". Pressure canning recipes in the US are based on times and pressures in a pressure canner - the foods will be under-processed using those recipes/guidelines using a pressure cooker. Canner/Cookers also usually have slightly different cooking times for pressure cooking than plain pressure cookers.
I also have no idea about the pressure cookers sold in Greece (the UK, Sweden, Germany, Poland, Iraq, Lyberia, Chad, etc.) - or if Greece has an equivalent to our National Center for Home Food Preservation site that might have tested and proven safe methods for pressure canning using the pressure cookers commonly available in Greece. I spent about 30-minutes looking and didn't find one (I might have but it was in Greek), but like you said McNerd, "if you took the time to research it you would know that too."
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain