Can 당신 help me?

1st off, u don't cuz the shoulders u cut the threads that hold the sleeve to the shirt. that keeps the fabric from shredding. it appears she cut all but the arm pit threads. the rest of this is a best guess...

leave roughly a half inch at the 상단, 맨 위로 and bottom of the sleeve when 당신 shred it. it looks like each piece is about 1/4-1/2 inch thick as well. use scissors carefully so 당신 leave the half inch at the bottom and don't cut all the way through.

as for the neck, do the same thing only start just below the thicker part of the neck of the tee. I'd suggest turning the 셔츠 inside out and making the v shape with a marker so 당신 know where to stop with the scissors. 당신 also have to LEAVE THE SHOULDERS IN TACT!! if 당신 cut the shoulder threads the 셔츠 falls apart. 당신 can even see part of the right shoulder in the picture. i'd say leave 1/4-1/2 inch on either side of the shoulder stitching. it looks like she cut out the strips of fabric between the cuts, unlike in the sleeves. i'd guess she took out small strips and left those narrow ones 당신 c.