RG robots can find just some of "ones' " published Items, the rest or what ever you have, should be added manually by you yourself. By using "add research" tab, in blue color somewhere near in the middle right corner of your page.

See this help page ("How to add research") for detailed instructions how to add published or unpublished research to ResearchGate: https://help.researchgate.net/hc/en-us/articles/14293005132305