When you want to upload a positive seed set to a project before you have started screening, you select the “Upload Seeds” button. See question above: Creating a New Project > How do I use a training seed in my project? for more information about seed sets.
SWIFT-Active Screener supports a variety of file types for import: PubMed XML (eXtensible Markup Language) files, which are results of PubMed searches saved from the PubMed website, EndNote XML, and the standard bibliographic file formats BibTeX and RIS.