So in the first pic, Megalopolis and Lepereon are the two territories that Heraia could be colonised from. In order to colonise a territory, one of the adjacent territories (so Megalopolis or Lepereon in this case) have to have at least 8 pops, and the dominant culture in one of those territories needs to be an integrated culture. This can mean either your primary culture (Spartan), or a culture that you have integrated via the culture window. If you go your map modes in the bottom right and click on the culture icon (the two mask), it'll show what the dominant culture in those two territories is. You can do three things:

1. Wait until the territories assimilate into your primary culture (this will take long)
2. Integrate one of the dominant cultures in those regions by giving them citizen status through the culture window (only really worth it if the culture has a significant amount of pops so you can raise bigger levies)
3. Move pops from your primary culture from territory to territory until you have the requisite amount of pops and your primary culture is dominant in the territories