How to Make New Font

Hi guys.

I just wondering how to make a font for selling in graphicriver.net. What kind of software should I use to make a font? I have a friend who sketches fonts very well. Now we need to know how we can convert his fonts. Which format we should upload to graphicriver.net to sell fonts.

Thank you for your help.
Best Regards.

Here are some programs that I found.

-https://www.fontlab.com/font-editor/fontlab-studio/

-https://glyphsapp.com/

-https://doc.robofont.com/

You should probably upload both a TTF and OTF.