See this help page ("How to add research") for instructions how to add published or unpublished research to ResearchGate: https://help.researchgate.net/hc/en-us/articles/14293005132305
By the way, there may be publications not yet attached to your profile, but available in ResearchGate. There are at least two possibilities to find these:
1. Look at https://www.researchgate.net/profile/Rachid-El-Guerjouma/unconfirmed (visible only for you).
2. Search for the titles of your missing publications at https://www.researchgate.net/search.Search.html?query=&type=publication
Then confirm authorship to attach these to your profile - see https://help.researchgate.net/hc/en-us/articles/14292798510993 for instructions.