Hi @Blackbee welcome here 
It is usually best to source these new members one by one and talk with them to join the community. You’ll want to do this after you’ve defined what kind of members or users you want in your community. I usually do this by defining a persona for my community. This post helps with this: 6 Steps to Building Community Member Personas | by Katie McCauley | CMX Hub | Medium. If this post isn’t helpful enough, do let me know, I plan to write something on this soon.
Once you defined the ideal member you want for your community, the next step is to find a few of them, and one by one, identify their needs with respect to what your community will be about.
Once you have an idea of what their needs are, you define experiences that pull them to your community. These experiences could be you inviting them one on one or something more elaborate, but do not “launch” your community, just bring on members one by one to meet the experiences that satisfy their needs.
You’ll want to do this personally and manually so you get to know them and onboard them.
To find them, you’ll want to meet them where they are, you defined this in your persona, so use that here. This is not to be rushed, so take your time because once you get the right people to start your community, you’ve built the right foundation. The right foundation is key.
On structuring, I generally prefer to let the community guide me on what they want to see in the community. You’ll need to have defined their needs and pain points like I mentioned earlier and from there you know what they need/want and you can structure from there.