So, here are the pictures on how to braid your hair yourself, classic style (I am still working on a good take on french braiding...)
You start out by collecting all the hair into one single ponytail. I advise against using a hair tie at the start of a braid since that has the potential to break your hair due to too much pressure. It is OK for practicing, but later on you should be able to make braids without the aid of a tie.
Then you part your ponytail into three parts of somewhat equal thickness. Best is if you part the ponytail first with one hand and use the other hand to separate the strands on the whole length. Afterwards, you put two strands in one hand and the third in the other. This is the usual start of a 3-strand-braid.
I am left-oriented, so I start by pulling the left strand over the middle strand.
And then the right strand over the new middle. The rude gesture is allowed for visible fingering...
The next step is holding all strands in one hand and separating the hair length again. If you don't do this, the hair will braid itself from the bottom up, and this causes no end of tangles.
Afterwards, you return your attention to the left side and pull the left strand over the middle one. Now is the time to adjust the braid - pulling it slightly to the left or the right, up or down, as necessary.
The strands should now be stable. Right over middle.
Continue to the ends...
...and tie off with a scruncie.