There is a Community feature on HIVE which you can find HERE although we do have more of a focus on just posting using the #SilverGoldStackers tag as it's a little more accessible and inclusive for non-members.
We also have a Discord channel where a lot of us gather who don't use HIVE, you can find that HERE
As for joining formally, there is a process is detailed HERE but you don't have to be a member to post about precious metals to the #SilverGoldStackers tag. Indeed, doing that is the best way to get started and get nominated for membership.