So i made a video of me soldering the headers on. My hand covers alot of my soldering but i think people can still get the general idea.
Very cool. Greate community and great senior members 
Very nice.
One of the things that I have gotten into the habit of doing is using little blocks and things to make a very primitive jig to hold headers and things while I work. In that case, I would probably Set the headers up to be held in place with something while I tacked them with one pin soldered, then went over it again before soldering the rest of it up. Tape works too, however
Blu-tack. Do you have it in the US? Works wonders for holding semi-rigid things in place nicely
Nice video. Great you showed that you should solder only 1 pin and then check the alignment of the header before soldering the rest.
Very clear, although you should get some more light next time 