nice machine. and plz don't be offended, i understand it may not be your career, but take some time and practice.
watch a few videos maybe.
referencing this pic above of the rear frame work.......welding is not like glueing the 2 parts together, that's basically a lot of what you got there.
very little of some of that looks to have actual penetration.
it seems you may have had some trouble getting a good arc start in several places. maybe the wire feed is set to fast or the powers low or the grounds not solid.
i try not to call people out on this, i manage to not rag on most marginal welds but those are on the crap side of mediocre.
get some scraps, if you watch some video you can get it down pretty quick. 85% of it is setting the machine right for the material. the other 15% is how you move the gun/wand/stick.
clean the mess, it's not easy to weld through mill scale, rust and paint, and leaves garbage in your welds.
the machine will do the work. you just have to find it the right spot/setting for your material thickness and then it's just moving it along at a steady pace.
that wire needs to touch both pieces in the corner or on the seam. if you have a gap you would move the tip in such a manor you could contact both parts, this will melt your wire into both surfaces. and the speed and manor you move along will control the amount of filler you deposit (your bead).
the stinger essentially melts the surface of both parts allowing your wire to melt into it, become part of it, as it melts in it also deposits a bridge or bead. failed penetration is just glue, that will fail.
any of that stuff that did not get penetration will crack away and you'll see rust under it next yr.
don't take this as a rip, take it as safety advice or an opportunity to get better.