Pablo,
Your PIC time in aeroplanes gives you 7 hours credit towards the 15 hours in sailplanes before you can apply for a SPL. In the remaining 8 hours of training you will need to do at least 3 hours dual, 45 take-offs & landings, 2 hours of supervised solo & the 50km/100km navigation flight. (FCL.110.S & 210.S)
You will also have to do the glider specific exams in principles of flight, operational procedures, flight performance & planning, aircraft general knowledge & navigation. (FCL.215)
The syllabus is in AMC.FCL.110.S; 210.S.