How to see/alter code for entire site, rather than using code injections

Site URL: http://rust-coconut-kf7x.squarespace.com

Hello - 

I am not a coder, but in the past, I've built websites and deeply modified blog pages, all based on being able to see in context why things were the way they were.  

I feel like everything I do in Squarespace, I have to look up, because it's not very intuitive, and in fact very frustrating.  (for example, why do I need to add spacers to change the size/alignment of an image?  Why can't I just choose what size and alignment I want?  In fact, I can't get one of my images to center when using spacers. It's either to the left or the right, no matter how much I alter the spacers and image size. It's a PAIN IN THE NECK!)

Is there a way to see and alter the code for the whole site?  This allows me to "play" with the code until I get the respective results I want.  It would save LOADS of time trying to dig through their help, forums, chat support, etc..

I do understand Squarespace cannot offer full support if code is altered, but the time I'm spending looking things up is getting ridiculous.

If you need to code to center image, you can share link to your site, we can check & give the code