If you are using the moodle WYSIWYG HTML editor, you don't need to know or use any HTML code. Simply use the editor to format the test/images etc. as you want them to appear and that will be fine.
One thing to note is that if you want to set the appearance in terms of positioning elements within your content, you will need to bear in mind that this editor (and any other you may use) will not necessarily have the same width as the content when it is displayed. Without using HTML/inline css etc. the easiest way around this is to set up the display of your content area using tables - also availabel within the moodle html wysiwyg editor.
In terms of using other alternatives, software like OpenOffice Writer, MSWord or other wordprocessors are not really a good idea, compared to other tools available, as they can add additional/hidden code. But there are many alternative dedicated html editors and website development programs available - it really depends on what system you are using (Windows/Mac/Linux) When not using Moodle, I tend to use Komposer on my LinuxPC - although in truth, I often turn to a blank moodle course page to use the moodle editor when creating pages for outside moodle as well - I then cut and paste the code out of moodle to my other page - basically the opposite of what you're asking ! lol!!)
HTH
Richard