When on a Phonemos page, use the “…” menu on the right side pane and choose “Import content”.

Import dialogue
Supported import formats are:
MS Word documents: .docx
Open Document Text: .odt
Rich Text Format: .rtf
Markdown: .md, .markdown, .gfm
HTML: .html, .htm
LaTeX: .tex, .latex
MediaWiki: .mediawiki, .wiki
DokuWiki: .dokuwiki
Phonemos Archive: .phonemos.zip
ZIP archives: containing supported formats