need photo conversion help

I took some great photos with my Nikon Cool pix camera. unfortunately I used the highest resolution so I could resize for internet posting and have prints if one is justified. Anyway the problem is that the camera saved the photos as a .TIF file and as such cannot be uploaded to Ferrari Chat. Can you help either how to upload or convert to .JPG so I can share these photos with the Ferrari community? I used Nikon software for the transfer to my computer but have not deleted the files from the camera just in case. Thanks for the help. Jon in Delaware