[X-Newbies] xls files

[Keith MILLS]

Sorry if my question may yet again  seem naive, but I should be 
grateful for advice.

I have received two different xls files. According to "The Missing 
Manual" I should be able to drag them into Stuffit Expander and open 
them. All I get is - could not be converted to Appleworks file. Have I 
misunderstood? And is there anything I can do?

I am on 10.3.3.

Many thanks
Keith