The easiest way to create a PDF version of your document is to load it into LibreOffice http://www.libreoffice.org/ and to export it to PDF. This software is free and available for most platforms.
Another easy was is to install a PDF printer, such as the free PDF Creator http://sourceforge.net/projects/pdfcreator/ or the free software Bullzip http://www.bullzip.com/products/pdf/info.php for Windows, or Cups for Linux. You open your paper in your word processor and print it by selecting this printer. The printer will actually not print on paper but will produce a PDF version of your paper.
As some PDF creators, such as Architect 3, seems to be incompatible with pdftk (the software used by MPRA to generate the cover page), in order to avoid rejection because of compatibility issues, please print your paper with a compatible PDF printer as mentioned above.
If your work comprises several PDF files (such as parts or chapters), please join these files into one single file by means of a utility like pdfsam (http://www.pdfsam.org/) or Adobe Acrobat.
If you want to supplement your contribution by providing files in other formats than PDF (text, machine-readable code, Excel, etc.), please embed them in the PDF. You can do this by using Adobe Acrobat or by using the free utility pdftk (http://www.accesspdf.com/pdftk/). If you want to attach the files table.xls code.txt to your paper.pdf, for example, use the command
pdftk paper.pdf attach_files table.xls code.txt output out.pdf
which generates out.pdf containing your paper with the attachments.Go to your User Area
Note: If you encounter problems with producing and uploading PDF files, ask a colleague or friend for help. We can answer e-mails regarding such problems only in exceptional cases.