Do understand this : there is NO such thing as 'converting to WP' WP it'self varies so greatly it would take a dozen posts migrating to explain migrating from one theme to another VERY different theme ( some themes are just the same theme reskinned.. and some themes are child themes)
So lets face reality. You are building a new site from scratch.
Note this may be a good point to consider a new design(look) But you could copy the look of the old site.. either way you will be rebuilding it from scratch.
A site is really composed of:
content : the text and pictures that are info
structure: that's the HTML mark up .. this is part of what WP generates
and design/layout : coded in CSS and may involve graphic design and art direction
it also has "info architecture" this is the ORDER to pages and content
The best place to start is to install WP and .. THINKING about your current content create an "information tree"... a diagram of what goes under what category or label. Think of those company structure diagrams, but for articles and info
Now you can go into the WP dashboard and essentially create the same tree by creating categories /sub categories or pages/sub pages .. if you really have picked up on WP you can create CUSTOM taxonomies ( that is custom fields for the info entered for a specific category/sub categories.. this will require not only knowledge of WP, WP dashboard, but also of WP codex and basic PHP.. possibly AJAX). Chances are you wont chose going that way so I wont elaborate.
Once you have created you categories ( info tree) you can now copy paste your info in the WP dashboard. ah, the tedium but that's about the only way.
Assuming most of your info was a Title/data structure .. you are relatively set. If not you will need to consider getting a theme that can handle more complex data structure or if you know PHP and WPcodex tweak the existing theme so that it accesses the WP DB and displays all the info you want.
Remember as you are doing this make sure that the output is HTML as clean as you can get it.
At this point you should have a good, plain HTML site for which you can create a design in an image editor , slice it and code a one or more CSS style sheets ( since you know the HTML structure that WP will output and Wp is really good ad adding ID and classes for CSS hooks)
That would be a good strategy for managing this project. As far as learning the specifics, well there is no shortcut for that , am afraid.