That's an excellent question. Use a larger wire for the trunk. One larger wire works better than two thinner ones. Copper is better for pines than aluminum, but you are doing fine as a beginner. Start off as you did, but take your loop a little closer to the crotch where you cut the trunk. Then pair off the other branches. It takes a full turn around the trunk between the two lower branches to anchor properly. Follow your wire just like you did on the trunk. Then just wire the crotch at the top as I showed.
Here's an old wiring article that I need to update but can get you started.
The real question is, does this tree have any back branches? You need to build some depth in the future. Your tree may bud back if you treat it correctly, feed it well etc. Search this forum for articles on mugho pine. If not, you can always
graft a new branch where you want it.
Be careful about your soil mix. I fear it will hold too much water for this tree. Good luck and leave it alone this year!