You can share your paper on this platform as working papers.

Thanks.

Nikos Lambridis you can do that by clicking on the blue add research button. And then if it is published research, Conference paper, etc

Thanks, Stefan; I will do that now.

Cheers

It depends on what you mean by "publish an arcticle". See this help page for instructions how to add published or unpublished research to ResearchGate: https://help.researchgate.net/hc/en-us/articles/14293005132305-How-to-add-research (Stefan Lindstrom has already given the main point of the instruction). But please note that ResearchGate is not a publisher and not a journal, you cannot "publish" (in the narrow sense) here. It is a platform for articles published in journals, or to present unpublished texts, data etc.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.