Hi, were they desktop bookmarks (Windows, Mac, Linux) or mobile bookmarks? Sync should work automatically after you sign in, while Firefox is idle. It might help to tape Sync now on the menu. If nothing seems to happen after a while, you can investigate what is in the Sync cloud for your account. I only know how to do this on desktop (see: https://support.mozilla.org/en-US/questions/1506488#answer-1726222).