I can't find
ubuntu-10.04-destktop-amd64.iso on http://www.ubuntu.com/download.
Where I can find it? Thank you
Here you go. Just click on the link to download...
"Intel x86" means 32-bit and "AMD64" means 64 bit, If you didn't know that. I don't get why you want to get 10.04.x because it is a EOL (End of life) releases on the desktop and remember that getting updated software to work can be hard so use this to help you with that "How to install software or upgrade from old unsupported release?". I also recommended you not to use it as a daily os but to just show it is just fine.
this is the link you want. http://releases.ubuntu.com/lucid/ubuntu-10.04.4-server-amd64.iso . just click at that link to download the ISO. But havent found desktop ISO but you can install the desktop later . To choose the desktop you need please look at this question.