I guess you mean to publish an article (also called paper). Please note that ResearchGate is neither a journal nor a publisher, you cannot "publish" a paper here. It is a platform for papers published in journals, or to present unpublished texts, data etc. See also "Is ResearchGate a publisher?" in https://help.researchgate.net/hc/en-us/articles/14292596164753 and this help page for instructions how to add published or unpublished research to your ResearchGate profile: https://help.researchgate.net/hc/en-us/articles/14293005132305-How-to-add-research. When you present previously unpublished research results here, this will not be regarded a publication.