These are are different colour schemes for my portal in my FMP, to change the colours i used the hotkey CTRL+U to bring up the Hue and Saturation menu while in this menu you can change the Hue, Saturation and Lightness, my first colour scheme was pure red, orange and yellow but then i decided to play around with different colour combos to make the portal blend with the background colour.
The portal is going to be a rip in between worlds for my demon creature to try and destroy the sirens home.