First you get your muscles built up, or you get a tractor with a bucket and a cement mixer. Then you take your compost pile you have saved and worked all year on and blend some salmon remains and manure in and potting mix and pearlite and soil and peat moss and mix the hell out of it until it has fully evenly mixed in your cement mixer and become nice and fluffy super potting soil consistancy. You do that over and over with load after load because your cement mixer won't hold enough for even one tree, then you blend and fold it all together again with the tractor bucket.
You can use it right away, but it's best to let it sit covered and cure use it months later fluffing and mixing once more before use.
If you can't do all the above then you just do what you can... Planting those in only outdoor dirt won't get those results, not even close, but you could use other nutes and good potting soil if organic isn't your thing. Probably won't work as well though, there is something to be said for organics and all the bugs and microbes etc it will gain.
Subcool has a great super soil recipe with quantities if you search it out. Not sure he uses the same recipe but it's a similar concept.