as OpenELEC told you, simply reboot your system...
in OpenELEC under System, OpenELEC, System, Updates, there are these three options:
Automatic Updates: auto
Show Update Notifications: *
Check for updates now: *
... but i think this will not update from OpnELEC 3.x to 4.x.
or it is still not available as automatic upgrade.
on my system i had to do this...
but you can update your version with help of a second computer.
your OpenELEC shares some folders as network shares.
there is a shared folder with name "Update"
from windows, you open it in file browser by typing in
(where you have to take the IP address of YOUR RaspberryPi)
download the "OpenELEC Stable - Raspberry Pi ARM" from:
http://openelec.tv/get-openelec/downloa ... -pi-builds
open that just dornloaded "OpenELEC-RPi.arm-4.0.0.tar" (e.g. with 7-zip from 7-zip.org)
take the files
from the folder "target" from inside the compressed file
and copy them to the Update folder network share to your RaspberryPi.
now you can reboot your RaspberryPi and OpenELEC upgrades automatically.
on next boot, you will see messages like
check system... ok
check kernel... ok
or similar messeges, and Open ELEC reboots again. after that, OpenELEC starts up with its new upgraded version OpenELEC 4.0 with XBMC 13.0.