Certain core pages, such as the page for the Vaktovian Empire and Vaktus are admin-only. As for pretty much all the other pages, if you still cannot edit them, try creating a page. I believe contributing helps your account no longer be considered "new."
Sorry about my page, wanted to explain that I might be coming back but my initial account that I first used for the VAC was hacked. I'll probably make a new one in a few months if I ever return to ROBLOX.