I think I should find another way of installing android. if any ideas or suggestions or ways are available please share them with me

Again, those one line post are not helpful. How do you want to install nitdroid, if your package management is in a twisted non-functional state.

Please provide the output of the commands to look at it. Helpful people will chip in to get things sorted somehow.

Here is how Copy'n'Paste works best for you:
If you run a command in X-Terminal application, an arrow symbol is displayed in the lower left corner, click it to activate the output of the command and the command itself, select 'Copy' from the status bar to paste the activated parts to the internal 'clipboard', select the browser to go to this very topic and select from the browser status bar menu 'Paste' to get the clipboard's content to your next post in the thread

Nokia-N900-51-1:/and# dpkg -i /home/user/MyDocs/nitdroid-kernel-2.6.28-07_rc4_armel.deb
(Reading database ... 37748 files and directories currently installed.)
Preparing to replace nitdroid-kernel-2.6.28-07 rc4 (using .../nitdroid-kernel-2.6.28-07_rc4_armel.deb) ...
Deleting leftover 2.6.28.NIT.07 modules in Android...
Deleting leftover 2.6.28.NIT.07 modules in Maemo...
Unpacking replacement nitdroid-kernel-2.6.28-07 ...
Setting up nitdroid-kernel-2.6.28-07 (rc4) ...
Copying 2.6.28.NIT.07 essential modules to Maemo...
Running depmod...
Creating item file for multiboot
Nokia-N900-51-1:/and# leafpad /etc/multiboot.d/11-NITDroid-mmcblk0p2-2.6.28.NIT

it redirects me to leafpad from there and nothing happens

Are leafpad and multiboot installed???
Are you sure that you type the name of the file correctly? Try to use the <TAB>-completion of the X-Terminal application: You <TAB> button on the lower bar of X-Terminal. Type the first letter(s) of a command and let the X-Terminal help you, like this:
If leafpad is missing and you cannot install it, there are some text-editor for the X-Terminal installed: mcedit, or vi or nano. But their usage is quite different from the GUI-editor leafpad.

Edit: You might post a link to the tutorial you are following to install nitdroid.

I think multiboot is missing, I've tried installing it but it says not available

Soback to repairing your repository list, which seems to be corrupted.
One of the reasons might be the usage of the built-in Hildon-Application-Manager, aka. HAM, mixed with the pure apt-get from X-Terminal. The HAM application never played nice with manual installs.

Please edit your repositories only in the HAM section to manage repositories. Check those repositories for being typed correctly and being enabled (NOTE: The nokia repository's names are translated into your localized settings):

Catalog name: Nokia Applications
Web address: https://downloads.maemo.nokia.com/fremantle/ssu/apps/
Distribution: ./
Components:

Catalog name: Nokia System Software Updates
Web address: http://downloads.maemo.nokia.com/fremantle/ssu/mr0
Distribution: ./
Components:

Catalog name: maemo.org
Web address: http://repository.maemo.org/extras/
Distribution: fremantle-1.3
Components: free non-free

For qtedger to work you need the CSSU installed,

Catalog name: Community SSU
Web address: http://repository.maemo.org/community/
Distribution: fremantle
Components: free non-free

but you could uninstall that to skip setting up CSSU for your Nitdroid intentions. There might be also an OVI repository. Do you also have extras-devel repo enabled???

Catalog name: maemo.org extras-devel
Web address: http://repository.maemo.org/extras-devel/
Distribution: fremantle
Components: free non-free

HAM will update the repositories, you have to be patient...
Reboot to kill all the HAM actions after the update of the repositories, AFTER!!!

Now try to correct the package management systemPlease post the output of all the commands here if errors occur, that are not finally after running all the commands, are resolved.

Unpacking replacement kernel-power-modules ...
dpkg: error processing /var/cache/apt/archives/kernel-power-modules_1%3a2.6.28-10power52_armel.deb (--unpack):
failed in buffer_write(fd) (9, ret=-1): backend dpkg-deb during `./lib/modules/2.6.28.10-power52/ipt_LOG.ko': No space left on device
dpkg-deb: subprocess paste killed by signal (Broken pipe)
Errors were encountered while processing:
/var/cache/apt/archives/kernel-power-modules_1%3a2.6.28-10power52_armel.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
/home/user #

No space left on device!!!
First try to get back some spaceThis purges the install packages downloaded previously.

To get information about the space on the device:
Please post the output of The first command shows the mounted partitions, the second lists the free space on the mounted partitions, the third shows the RAM and swap space, the forth and fifth list the 20 largest directories of the rootfs and optfs.
Warning: There is a 'pipe' symbol in the last two commands, it can be accessed via the blue function key and the <Sym>-key.

I hope not. As.has been mentioned repeatedly, extras-devel is not for the average user.

I bet most of the space is taken up by Android, not the pachage cache. I would look under /and. Michaaa62's du will highlight that if I'm right.

its funny, when I now go to images and tracks, it says no images and tracks but I can see them in file manager. sms's also say sant send nor receive due to low memory but I have more that 20Gb free memory.

I just ran the commands and hope for the best