right. you have now
selected bytes from start offset 0 to end offset 1F (= 20 - 1).
0x0 - 0x1F
View attachment 5826731
on the left column you see
offsets. on the bottom you see block selected
0-1F + length
20 (h)ex.
copy these two lines with ctrl + C. it is now in clipboard.
next, in menu 'File' -> create
new empty file.
paste the two lines from clipboard into new file with ctrl + V.
now, in menu 'File' -> save the file ->
bobbywan30_exercise.bin
congratulations, you have extracted your first file yourself.