CSS Mysteries or Miseries

When editing my main content panel - the only one I have done so far - on the 'Edit ContentPanels' page it gives the option to use Cascading Style Sheets if you understand CSS.
I understand CSS as I use it all the time in my web design work and I am sure I can work out how to change the default font on the content panel etc ( although I would like to know without trying to de construct the source what tag has been used to define the 'Description' of each panel that appears at the tip of each panel under the heading?

However what I most want to do it change the style of the panel headings!
As currently I am mostly using the built in template 'rounded' but I do not like the colour, which is blue - I would like to change these 'rounded' titles to a different colour.

Can this be done with CSS and if so what is the name of the tag has been used to define the panel titles shape and colour? ( as it must be a custom tag and I can not as yet work out what it is from the source as it refers to a pre-defined template stored elsewhere on the server) Or do I have to write a new CSS template – if so where do I post it – do I post it on the server or do I post the code for it on the edit content panels page? When positing CSS in the input box provided do I have to use the ‘style’ tag to enclose the CSS – or if you enter CSS in that box without the 'style' etc will it know that it is CSS

Can anyone help me on this? - I am happy usually to work things out myself but feel the need for a proper help section on these sorts of aspects of plone which I have looked for but can not seem to find ....
Am I missing it somehow as the only explanations I have found on how to do things so far are from the odd tips in here or in specific areas - i.e. in the content panel properties pop up window, it says at the top that you can use this window to change what the panel displays but there is no proper help/manual/reference available that I can find?
I have extensive internet experience of many different systems but not this one - and the way I like to work is to have a proper online 'manual' reference or help section about the technology and work it out from there so I can make it do what I want it to do given the limits of the technology and any permissions granted to me ( i.e the extent of which my status within the system allows me to alter and adjust things)

This way I feel I am working blind - for instance how can I use the technology to the full if I do not even have a basic reference/ manual/software explanation/help section that tells me what the software is capable off?
i.e I am asking you what CSS tags to use to redefine content panel headings design and yet I do not even know if this is even possible !!!!
I find this very frustrating, as this is not at all how I am used to working.

Is it me - have I just not found the manual or help for users of Plone? Or am I somehow failing to get my head round how this specific system/technology works and it is quite obvious how to get the answers I need apart form having to write a long request here rather than just search a manual or help database to find the answers for yourself?

Sorry to be a pain - but I think I am finding it harder because I write web sites all the time and know the programs I use inside out and I am not used to not knowing - so because I do not understand fully this system and can find no obvious reference to learn it - i am getting frustrated that at this early stage I can not have my area looking as I would want it. I agree it is a learning experience for me and challenging, but I would hope not to have to guess and try things out so much to learn – I find this a time waster of time I do not have .

Thank you

Veritee