There are three key tools you can use when customizing your LibGuide with code:
I recommend learning them in that order, as each one builds upon the previous one.
If you want to learn more about HTML and CSS, I recommend some online courses that will teach you the basic and intermediate level skills:
for Bootstrap, the most helpful resource I found is the Bootstrap documentation:
For a partial list of LibGuides {{curly bracketed}} content that you can add or move around in the HTML on your pages, see: http://support.springshare.com/libguides/guidetemplates/customizeguidetemplates#s-lg-box-3821
If you would like to see what Kingsborough did with these tools, you can see our LibGuides at http://kbcc.cuny.libguides.com/
If you would like to see the code we used to make the Kingsborough LibGuides, you can find it here: https://github.com/MarkEEaton/Kingsborough-Libguide