I am looking for a search function in new numbers program on my iMac.

As already mentioned, Cmd F brings up the "search" (find) feature. That is pretty standard for apps on Macs, even for non-Apple apps like Microsoft Excel.

Find will search tables and text boxes and charts and whatever else but will not search within formulas. It will search the results of formulas but not the formulas themselves.

Edit menu > Find

or command F