When it comes to journaling your meditation sitting,
You can start by writing down the parts of meditation sitting that you recall most easily.
Once you've written those down,
You'll find that other parts of sitting may be easier to recall.
In writing down your meditation experiences,
You can write in complete sentences,
Or you can use phrases,
Or you can make a list,
And some people might want to use a mind map or illustration in order to get at some of the connections and things that were going on during the meditation sitting.
Your journal does not have to be a complete,
Accurate record of the meditation sitting.
It just needs to be an honest recounting of what went on for you.
When you're writing about your experience in meditation,
You might find that you tend to use the same words again and again,
And see if you can try to describe certain experiences that in the past you've just used a label or some kind of umbrella term to describe it.
For example,
If you write down that for the last 10 minutes of the sitting you were bored,
Then try to give a fuller description of what boredom is like.
This may require you to go back over the journal and look at certain things that you put in and just fill them out a bit more.
When it comes to the length of the journal,
Maybe a couple paragraphs,
A page,
Would be sufficient for the time being.
Sometimes people,
When they're meditating,
Will think a lot about what they're going to write in their journals,
And that may interfere a bit with your meditation sitting.
So if that starts to happen,
Then decide not to journal until after the meditation sitting is over.
And some people feel that they might like to write during the meditation sitting.
That could be something you try once or twice just to get started in remembering experiences in the sitting,
But I suggest that for the most part you wait to journal until after the meditation sitting is over.