To open the text file on pspp (you must be exported it as a csv), you first need to open pspp. I assume you are using windows, so you should find it on Start -> Program Files -> PSPP -> PSPPIRE. But, if during the install you choose to not create shortcuts,you
will have to find it on the filesystem, probably on c:\program files\pspp\bin\psppire.exe
About the "converted" files to pspp, what happens is that the file association has be changed from spss to pspp. If you want it back
to spss, right click on any .sav file, chose "open as" and then select SPSS from the list.