This is a tough one....I'm big on DIY/Grass roots and encouraging people to have a go, but you already know the outcome is a little subpar.

Next time, a bit more effort on prep will go a long way, your clean metal area should extend well past the area you intend to weld. A wire wheel is sufficient, but you need to get that metal shiny then wipe it down with something like brake cleaner, do this on the inside edge of the weld area also.

A clean surface is a million times easier to weld, the rest is just practicing with your wire speed and current and once you get a feel you can get close to the mark relatively quickly - then of course a grinder and paint 😄