In /boot/grub/grub.conf you will find the line "default=0" perhaps. this refers directly to the "title" line where 0 is the first number and 1 is the second and so on. If you want to swap the boot order, you can either change "default=0" or whatever to "default=1" or whatever, or you can move the chunks of boot stuff in your grub.conf file. Since you are a beginner it would probably be easier to simply change the default boot number.
I would save your grub.conf as grub.conf.orig just in case you make a mistake.
(cp -p grub.conf grub.conf.orig).
All this is done as root BTW or in ubuntu "sudo su".