How to convert a file to xlsx

Hello, I have a document I scaned, I want to add it to one of my books as a worksheet.
What can I use to convert it to xlsx lets say from a TIF file. Or what is the best way
to save it and what is the best free software to convert it to a xlsx file... I need it
to be a xlsx file I can modify as if I made it from scratch... Thanks Raner...

Thanks Shg, Maybe that is why I can't any of the coverters I found to do the job...
Well Looks like I'm going to have to do it from scratch...I was just trying to get out of doing it...LOL...