Project Contacts

I have just started to test Zoho Projects after using Zoho CRM for a couple of months. I'm having trouble figuring out how we associate contacts with a Project? I've seen posts mentioning adding contact detailsin Zoho Projects, so I think it must be there and I just can not find it? This is separate from adding a user for a project as there are usually several contacts that are associated with any given project, experts that we call, etc...that we want to know who they were and what we spoke to them about, but they are not the client and/or project managers and should not have any access to the project portal.