This topic has been covered so many times a simple search would get you the answer but since you seem inept a searching I will offer some help. You are trying to run lilo of the live cd hence the "read-only" error. You need to either chroot into your new install or reboot into your harddisk install and then edit lilo to "see" your xp partiton.
What you should do is start over and use this method.It is the best method by far.


