Installing problems

[Ivan Soenario]

Dear Grassers, 

you may have concluded from the subject line that I am a beginner. Well, I
am. I am a student Physical Geography in the Netherlands and I'm very
interested in GIS-programs. So now I'm trying to get GRASS going on my
Pentium 133. Linux works, it's a REDHAT version. I don't know which one
(probably version 3), with a fresh kernel (probably 2.0.9).
I don't know about my gcc, libc or flex (how do I find out?) Hey, I told you
I was a beginner!
Anyway, I downloaded Grass 4.15 from:

ftp://129.229.103.1/pub/grass/grass4.1/release/binary/linux/

with the install.sh -file as well.
Unfortunately, this script gives error messages. Grass did unzip and go to
the right directories, but the installation is not finished, Linux doesn't
know about Grass yet.
Can someone tell me how to get install.sh working?

Thank you very much indeed,

greetings, IVAN