First thing you need to know about mods, Building, Compiling, & Java Code. Of course this blog is not teaching code but how mods must be structured and how to complete them. First you find any Java application that allows java code writing & editing, best might be Netbeans with Java 8 ( what ever the latest version of java is ). Netbeans is mostly recommended for beginners because it helps  point out mistakes ( most of the time at least ). This helps ALOT with typos or any wrong lines of code a beginner might mess up, so Netbeans is almost perfect for beginners who might make mistakes.

Next you should find a source for Java & MC code, maybe a class, online tutorials, or maybe by reading some books & articles on Java code.Then all you need  to do to get typing code, is finding ideas for your mod and textures.Which leads us to how to organize mods.
First you come up with an , IDEA, RECIPE, NAME, TEXTURE, DESCRIPTION, & ABILITY. IRNTDA for short as I continue to explain.
When these pieces are gathered together, you should store the IRNTDA`s in a booklet or packet so you have a source for your ideas when you start coding.But mobs require AI, & I`m not good with AI, so unfortunetly I won`t be talking about that, just orginization.

Finally, after you have finished, you must build your mod/project/addon so it is saved into many folders.Then you have to compile your mod so its not just alot of files minecraft can`t read ( learned the hard way trying to launch a mod but it crashed the game/ignored it ).Once you`ve done that you should test your mod or have someone test it for you, then check for errors & to see if it compiled correctley, otherwise you must find the problem immediatley, fix it, rebuild & compile & you`ll be done after any errors have been fixed.But remember this, mods & code require alot of patience, practice, & work.Don`t EVER get frustated with your mods & NEVER give up..... =`)