When you upload a tar, tar.gz file then you will be able to find a link in the column where you find the edit/rename links saying "extract". But i guess it works currently only with .tar and .tar.gz files. I am not sure about the others but may work for some more extentions too.
all what i know about DirectAdmin that it cant unzip .zip fiels
but when i try to buck up my sql it give me in .tar.gz
so i think it work with .tar.gz and .tar fiels only
bye