I recently shifted to linux...infact few hours ago. I am using fedora core 8 and I wanna use the gnuplot package. So I go to the add/remove softwares and type in "gnuplot".
I get the list I select it and then press "apply". Then after resolving dependencies I get this message
"insert fedorecore8 (disc1) " ----> I have two options OK and Cancel 
I have the fedora core 8 DVD inside the DVD ROM.
p.s : I had lost the fedore core 8 DVD which was originally used to install fedora core 8. So I recently downloaded .img file and burnt it on a DVD and inserted it.