How do I download e books from public library to my Kobo e reader? Thanks

I have been trying to download a e book from the public library to my Kobo.   I used to be able to this after the library helped me get set up.   But I did not use my Kobo for awhile and when I now try to download cannot do it.  I followed the instructions on the library page to download digital editions 4.0, but cannot seem to get book from my desktop library to my Kobo.   I have tried quite a few things (not very techie) but still not working.   Tried cancelling authorization and setting up again and not sure that was a good thing.   Now when I try to move book I get an error 'E-ADEPT-INTERNAL".   Went to Adobe help but a bit afraid to try their fix as it says I could affect my windows registry.  I am running Windows 7.

If anyone could help me I would sure appreciate it.   Thanks