Well Im ranked 580 and I have a steady grip over the neraby solar systems since there are no other strong players nearby. I found out the answers, but I just need to know how to change members's ranks?

Next to your rank on the alliance page, it should say (Manga Alliance;) once you click it go to Manage Members. Under the Functions thing on the far right, click the ~ button which will bring a drop-down box under Position. After you change their rank hit Save and you're done.