Get a font editor. With it you can see what data is included to fonts and you can as well edit existing fonts as create your own. There's no need to understand computer programming language level details of the font files if you use a font editor.
Warning: Copying parts (visible parts or rules for exact placing) of existing font files to be used as the basis of your own font is generally illegal as soon as you try to sell your own version or give it to others for free. Fonts are copyrighted computer software. If you download a font file you generally get also its license file. You can legally make your own versions only if it is clearly allowed in the license. If the license is missing it's no excuse for anything. It's your job to find the license and obey it.
Free font editors: Birfont, FontForge, Glyphr Studio (online)
I cannot advertise any commercial font editors in this site. There are numerous of them.
Drawing Program Inkscape has it's own font editor integrated but the results are in SVG format and can most easily be used in Inkscape. It doesn't open common existing font files.
Work tutorials to get started!