For the alt power bar, see how this addon does it:
https://www.curseforge.com/wow/addons/betterpowerbaralt
https://www.wowinterface.com/downloa...werBarAlt.html
For the alert frames, there's no single standard way Blizzard does them. I suggest using LS: Toasts instead of reinventing a personal solution.
https://www.curseforge.com/wow/addons/ls-toasts
https://www.wowinterface.com/downloa...-LSToasts.html
For image hosting, I suggest using
https://imgur.com instead, they aren't annoying with direct links.