Wanting to create a new system inside of roll20 from scratch

I guess my root problem is that I don't know where to begin and I think I bit off a little more than I can chew. I'm wanting to bring a system I've been working on into roll20 that is completely new. its design is simple, the character sheets are built by class with four abilities and a handful of stats. There is an item log that consists of 36 total items that grant various stat changes for combat. The out of combat particulars are handled by a 1d4 roll and that about sums it up. I have no experience in coding whatsoever,  so I don't know where to start with building the character sheet itself or adding in the 36 items into a compendium for the sheet, and to a larger extent roll20, to see and understand. If anything I need a point in the right direction so that I can get things at least off the ground. 

My recommendation is to start with a pen/paper version of your sheet.  Perhaps you've already done that.  This will help you determine what attributes you'll need to include and basic layout/design for creating your roll20 character sheet.  You don't have to create a sheet BTW.  Before sheets existed on roll20 everything was handled using the Attributes and Abilities tab of the character journal and a handful of macros.  You can still do this, but typically, having a sheet makes things much easier on everyone.  Not to mention that you'll want a sheet if you'll want to share your system with others. You'll need some basic HTML and CSS knowledge to create a sheet.  Lot's of tutorials on the web.  Read the roll20 wiki.  Building Character Sheets  More advanced sheet's may need some javascript as well ( sheetworkers ). You can add more features as you need them and/or get more skills.  Keep it basic to start with.  If you can create one input field, you can create 1000. I would suggest starting with an existing sheet, preferably something that's not too complicated. Look at the code and see if you can understand how the sheet is manipulated by the underlying HTML/CSS.  Use an external text editor like notepad++ to edit your code, use a custom sheet and copy/paste your code into your game's settings editor (html|css|translation|preview).  Save often and don't trust the preview window.  Load your game in another tab/window and refresh after you save your latest changes to see the changes with on your sheet in-game.  Ask lot's of questions on the forums.  ;-)

Vince gives great advice. I'd add some really strong advice: if your game is not yet finished,  do not  try to make a sheet for it. Making a sheet is a lot of work, with a lot of laborious testing, reloading, testing, etc. If you are creating your game system, and also having to constantly update your sheet, along with learning html and css at the same time, it will suck dry any motivation you have and you will make no progress. Until your game is complete, or very nearly complete, stick to using the Attributes and Abilities tab, and use them to test your game in play. It doesnt need to look fancy, it just needs to work.