Thank you for your help you may provide. I started from scratch and installed UBUNTU, now that is the only OS in the hard disc. I am going to install FEDORA to have a dual boot system ( as was my original plan). But with linux nothing seems to be straight forward .I do not know if this questions belong to anUBUNTU forum or if it is alright to ask it here (I assume it is because is to do a dual boot).
When I inserted the FEDORA disc and reached the point where the partitions will be modified I am presente with the following alternatives
1-Remove all partitions on selected drives and create default layout (I did not use this because I think it will erase Ubuntu)
2-Remove linux partitions in selected drives and create default layout (I did not use this one either because I think it will erase Ubuntu too)
3-Resize existing partitions and create default layout in free space (when I choose this one I get a message "COULD NOT ALLOCATE REQUESTED PARTITIONS .NOT ENOUGH SPACE TO CREATE /BOOT)
4-Use free space on selected drives and create default layout(when I choose this one I get a message "COULD NOT ALLOCATE REQUESTED PARTITIONS .NOT ENOUGH SPACE TO CREATE /BOOT)
5-Create custom layout -this take me to a screen that is something like this

Drive/de/sda(38147mb)
sda1 36538mb

NEW EDIT DELETE RESET RAID LVM

Device type format size (mb) start end

hard drives
/dev/sda
/dev/sda1 ext3 36538 1 4658

/dev/sda2 extended 1608 4659 4863
/dev/sda5 swap 1608 4659 4863


If I try to select let say /dev/sda1 then it start to ask for parameters I barely know about.. Basically I am stuck in the part of disk partitioning. I have been told that it is not important which system is installed first it is possible to do the dual boot. I installed Ubuntu first and the GRUB is in the MBR .If installing FEDORA first and then Ubuntu make it easier I will do it that way , whatever is easier and takes less time. Any further help will be deeply appreciated.( I have been trying to do a dual boot system for a couple of weeks now but always came here to ask questions after "both systems" were loaded and this complicated things. I thought it might be easier to have only one OS and then follow the instructions received to try installing the second one)

You can resize one of the Ubuntu partitions to create free space for Fedora, but very probably you need to do it outside of Ubuntu (the partition that is operated on cannot be mounted at the time of operation). Ubuntu live-cd or Knoppix or any other Linux live-cd that has GPartEd/similar or onto which it can be temporarily installed works. But probably it's just as easy to do one more reinstallation and instead of any automatic fill-the-whole-disk selections take the manual partitioning setup, read a little about partitions (Wikipedia might help) and create the needed partitions (boot (/boot), root (/) and swap at minimum, better make /home separate partition too), making sure you don't fill the whole disk -- leave some space for the other OS too, unpartitioned if you like. Then when you're finished, start installing the 2nd operating system, create the needed partitions for it in the space that you left free during the first OS installation (you can share/re-use at least swap and /home partitions between the two to spare space and make the systems share your personal configurations; just don't format them, only select their mountpoints appropriately in the partitioning tool) and that's it. Install bootloader to MBR; you can have both installers install it, that's OK, as long as at least either one of them does that. You might have to add the other OS to the boot list after the second setup, but not necessarily.

If you don't know anything about partitioning, you better start reading. Here are the basics:

- disk is divided into portions called "partitions"
- partitions have a filesystem; on Linux one of the popular ones is ext3
- you usually want at least /boot, / (=root), swap and perhaps /home partitions
- swap is not formatted the same way the other partitions are (just mark it as "swap")
- the partitions are connected to the system trough "mount points", which tell where in the system's directory structure they are in; root (/) is the top level, the others are below it
- boot stuff like bootloader configuration (or parts of bootloader), kernel etc. are stored in /boot; most of the system-wide stuff is on root partition, and if you have a separate /home partition, by default user data (anything the users have that is not system-wide; personal configurations, personal files, ...) is on /home
- you can create a lot of separate partitions (for /etc, /usr, /var, ...) if you like, but usually the ones are sufficient that I mentioned above; you can live with less too, if you need
- one GNU/Linux operating system usually needs one (it's own) root partition, but the others can more or less be shared between several operating systems; they are created and formatted once, then simply mounted in all the different distributions.