The more I learned how to code (still learning even to this day), the more I found the method to figuring out my problems. Hopefully this will help you and I'm sure I'll be repeating some if not all advice from above:
There are so many places you can go to get help and while you might encounter the occasional butt, you'll get the answers you are looking for. A few links for places I tend to go first if I need to look up code examples:
CodePen | A fantastic resource for looking for the examples you need and even use if you'd want to. It's a free library that you can draw inspiration from at any time.
W3Schools | In case you don't know about this one, this site is a great guide for new learners to people who are experienced. We're human, we all can't remember everything. It's a simple tutorial and a dictionary for all things code related. You need Java, Python, C++, CSS, HTML, more? A lot of it is there. They don't have everything but for building skins and templates for ProBoards and jCINK? They have all you'll ever need.
Stack Overflow | Do you have any questions about a section of code that isn't working properly or at all? This is your place. I've found this site extremely helpful. You can search your question before you ask it and I'm sure someone has already had the same issue. If not, you can always ask the community there. Most, if not all respondents, will give you a detailed response telling you what you've done wrong and how you can improve it.
Last but not least, you can ask around here. I've been helped multiple times on this site and the community has been great about it.
Always remember, if you don't do it already, test your code on the actual board it's going on. I know when I create things in Brackets or on another site, sometimes the code behaves differently when I apply it to the site I'm making it for. If it's not working in the application you're using, it might work just fine on the board.
Don't be afraid about "stealing" code. When people say that, I'm assume they just mean their specific design as a whole. But if it's a simple design, you can't get around it and just ignore it. Anyone can code three flat colored boxes that lay in each other. Especially if you're just making things to learn. If you want to take design elements that aren't particularly simple, try to make it your own. If it's still very similar, think about just giving credit at the bottom of the template or skin.
Lastly... just try to make a simple check list of things to look for if a code isn't working or breaks.
elli made an excellent basic list that works most of the time. I recommend following their advice. And like
bc said, the inspect tool in Chrome and other browsers that have it are your best friend. To access the inspect function, the usual method is to right click the specific part and click inspect. Control + Shift + I is another way to access it on Chrome, at least.
For Chrome, you can click the box with an arrow in it on the upper left corner to refine the location to get it precisely where you want it.
You can edit the code in REAL TIME and see it change before your eyes. This is great for figuring out what is wrong or mess with colors / sizes. Just click on the box of the element you're trying to edit in the inspect area. So, where it may show...
body {
background-color: #fff;
}
You'll click on that section to add code or click on something like background-color to edit that specific part.
I hope this helped a bit. Sorry it was such a long post. ; __;