Firstly dont beat yourself up over your first exam, you have identified the root causes in your post, not enough time and lack of concentration whilst studying.
Its air law, the dullest subject for most students wether ppl or atpl, like you I prefered the technical subjects as you can see or visualise the mechanics or reasoning behind the theory, air law you just have to read over and over till it sinks in, then get you hands on old question papers and/or feedback questions.
Break the study down into managable chunks, do you have an air law ppl book? these are usually broken down into managable sections with progress tests at the end of each section, I dont how the cd rom does it, but id imagine the book would be easier to refer to and study from.
Only book your test when your ready and achieving over 75% consistantly with practice papers.
my tuppence worth...
Best of luck