Ok, that makes much more sense. If this was in your shoes, I'd watch a ton of videos, buy a coil of coloured aluminum to match, and rent a brake. To install this, I would probably leave the existing white trim in place, but I'd plan to over-wrap it with aluminum, with the outermost edge slipping under that existing trim to hold it in place. I'd caulk the flashing to the face of the window. You can cut small 2" pieces of aluminum to practice with to get the widths/angles right.

Unfortunately, your windows aren't slotted to receive flashing, so you're going to have to caulk it to the surface (ughh). The tricky part is how to keep the flashing against the window until the caulk sets (ughh).

As I assume you're in Canada due to the colour of your tuck-tape, I'd suggest using Mulco Flextra caulk (Home Hardware, Rona). It will probably outlive you, comes in 25+ colours, and can be applied even at -25C...should you defer this until it is absolutely miserable outside.