You don't run Windows executable files under Linux, not natively anyway. You can look for a Linux equivalent of the software you're trying to use, or you could try
WINE. What was it that made you think you could run Windows executables under Linux?
For .doc and .xls files, you can definitely open those with OpenOffice.org (a free office suite), but other office suites or standalone word processors/spreadsheets may be able to open them as well.