How would one make notes relatively fast on pokerstars players.

Assuming i have a text file with 13 columns pasted from a spreadsheet looking like:
Fakename1 1584 * 11.5% * 4.4% * 1.4% * 88.7% * -5.3 /100
JohnSmith82222 1581 * 16.3% * 3.4% * 0.3% * 91.4% * 0.5 /100
Whateveruser 1545 * 5.8% * 5.1% * 3.3% * 74.2% * 4.9 /100
thisguy 1526 * 11.5% * 8.3% * 0.9% * 84.3% * -1.5 /100
thatguy 1498 * 21.4% * 15.2% * 4.9% * 66.9% * -4.9 /100
Russianplayer 1491 * 11.3% * 8.1% * 2.2% * 74.2% * -2.1 /100
TightTerry 1485 * 4.5% * 3.7% * 0.2% * 93.1% * 5.3 /100
LooseLucy 1480 * 25.1% * 6.3% * 0.5% * 55.9% * -8.4 /100

Normally what I would do is copy the name of user in my note editor and then copy and paste the rest into the notes and it automatically takes all spaces away, hens why I have * to separate each stat.

Is there any way of programming it so that thousands of players fields can be added? Also if I do this would I protect other notes.
For example, if I have a note on Russianplayer that says "Capable of making big laydowns" already, would it delete this note?

Check in your pokerstars user data folder for [username]-notes.xml - normal xml text file which stores the notes, you just need to manipulate this file. Do it while Stars is closed, or your changes won't stick.

how you deal with maintaining notes already there is down to your programming, but there's no reason you couldn't keep them or overwrite as desired.

You are asking someone to write this program for you? How how to program it? You just need to read from your input file, parse and format the text into strings per player, and then write/append to the correct notes.xml file.