its easier to use vi editor for this, run

sudo gainroot

vi /etc/init.d/rcS

scroll down to 263/281

press the letter i - don't press enter after

it looks like this
echo 100 > /proc/sys/vm/swappiness

use the arrows to move the cursor and change the value to 30 or whatever you want - keep it above 30 tho

then press the onscreen 'esc' button

then type this

:wq

then hit enter