File > Place
LOL! But seriously its the most efficient way to start.
just adding to what BOB said , While placing the file press the SHIFT key for Auto-flow otherwise you will see the first page of word file only with overset text.
Mind you: a Word file does not get "converted" to an InDesign file. Using File > Place, you get the text, some of the footnotes, tables, and endnotes (which always be at the end of the text run). You get bulleted and numbered lists, although at times ID messes up automatic paragraph numbering. You get to see imported graphics, but none of any objects drawn inside Word itself.
You do not get the same page size, margins, headers, and/or footers. If you are unlucky, you also don't get tables (ID cannot handle tables-inside-tables). Sometimes the importing process drops text boxes as well. Footnotes is a crapshoot -- more often than not you get them mangled up real bad. Sometimes you get bits of loose text at the very end of your placed text where ID could not find from where it came. (Adobe Support does not recognize this as a problem, by the way.)
And, lately, presumably with the very latest version of Word, sometimes you get nothing at all.
So you see: it's not a good statement to say that InDesign "converts" a Word document for you. You need to go manually over each separate line after importing.