Thank you for your advices.
I already download Acrobat SDK before, but it's really complicated for someone who know only VBA at intermediate level.
I really plan to learn javascripts and COM in future, but I was thinking that if I ask you for I guess easy think (opening files and saving them to pdf) you will help by giving similar code or some clues.
Anyway I found this two methods in documentation: PDDoc.Save and PDDoc.Open and I believe that a combination of them can finally help me. Do you know how I can connect them to one part?