I think that I need lightweight distribution of Linux os such like AntiX

so, first, i ask to know,
what the Official website address of linux Antix os? please.

http://antix.mepis.org/index.php?title=Main_Page

"Sudo is not configured by default. antiX is not Ubuntu! "
So how do I run it?

You could also have a look at these for help:

http://download.tuxfamily.org/antix/docs-antiX-15/FAQ/index.html

http://antix.freeforums.org/

If you’re not keen on antiX you could have a look at Puppy Linux, I like it, runs great on my Dell desktop.