Look for a program called IrfanView. That should be capable of the conversion of image formats. It is a free download.
If you want to get into being able to convert formats in batches, I’d also recommend GIMP Shop: rather similar to Adobe PhotoShop, but free, and Open-Source. Be aware, GIMP Shop is a rather large download, but well worth the effort.
I already have GIMPShop. 
After I converted it into .png, would I send it here?
Yes, use the attachment panel to send/upload the picture to this site.
Usually, as a safety feature, I take a copy each of both the original and the conversion, and upload the copy.
Be aware that you may have to make a few attempts to upload the image to this forum.
Reason is that recently the software here was upgraded, and it still hasn’t quite “settled-in” as regards functioning the way most members here are accustomed to it doing.
Kind Regards, Uyraell.
Imperial Japanese Army Ranks.
Santo Rikushi (Recruit)
Nito Rikushi (Pvt. Second Class)
Itto Rikushi (Private First Class)
Rikusicho (Superior Private)
Santo Rikuso (Sergeant)
Nito Rikuso (Sgt.First Class)
Itto Rikuso (Master Sergeant)
Rikusocho (Sergeant Major)
I will search more insignias for awhile… 
:army: