You can specify the crossword to be opened by choosing a file to open, or by dragging-and-dropping it onto the player. You can also paste plain-text-formatted crosswords into the "Enter crossword text" area.
Once you open a crossword, your state for that puzzle is automatically saved (it will be restored even if you revisit it later, after having worked on other crosswords).
Here are some details on the various supported formats: Exolve: You can open Exolve-formatted files with exolve-player. Such files have to contain a crossword in the Exolve format between "exolve-begin" and "exolve-end" lines. They can be HTML files too, as long as the Exolve-formatted data is present in them. PUZ: You can open .puz files with exolve-player. IPUZ: You can open .ipuz files with exolve-player. Text: You can open text files or paste the text into the "Enter crossword text" area and click on th