ok well i will start with the understanding that you have downloaded the file and that you know how to open a terminal ... so basically i am going to be saying what you have supplied, because it can't be really elaborated on any more than it is, so here it goes ...
in your terminal you will type (or copy/paste if terminal supports it)
chmod a+x j2re-1_4_2_<version number>-linux-i586-rpm.bin
where you replace <version number>
with obviously the version number in the file name .... so purely as an example :
chmod a+x j2re-1_4_2_1.4.0_02-linux-i586-rpm.bin
now what that command is actually doing is giving execute permissions to the file, so you can do the next step which is to actually execute it and for you can see that license agreement that they are talking about
so to execute you will put ./
in front of the filename so sticking with my example you will type something like the following (you will have to use the correct filename):
so then the next step simply says switch to root, which you said you were already root so i assume you know you type su -
and then type the root password ...
and then it says run the rpm command to install it, and the rpm command is simply rpm
along with some arguments, in which they use iv
... so you will type, again using my example filename :
rpm -iv j2re-1_4_2_1.4.0_02-linux-i586.rpm
and that would cover each step in as much detail as i could do .. hope this helps out, and don't hesitate to ask anymore questions