The Find text option appears at the top of the Xara Cloud browser window beneath the Status bar.
Pull up the dialog using the shortcut Ctrl + F - or if you have an object selected then you will need to use Ctrl + Alt + F (Ctrl + F in this case is the shortcut for 'bring to front' for an object's stacking order position).
You can also find the feature in the Documents menu - tap Find.
Just enter a search term - word or text selection (50 characters max).
With the text cursor in position the search starts from that point.
The search field will always contain the previous search term (for the duration of the current session).
Typing a search string does a real-time find of the first result only - hit enter to find the next one.
We're starting with Find - Replace Text will follow at a later date.