Some Suggestions
k8xp, I just took up riding a few weeks ago and went through some of the challenges you described (not able to turn, going straight down the hill and wrecking). I have been on Whitefish big mountain virtually every day to practice. Here are the steps I used to get to the point of split turns and then riding switch.
1) First off I am goofy foot, (what are you?). I learned on a NS directional twin (the legacy, basically a wide SL) but I now mostly ride on a full twin (Proto Hdx). I setup the bindings at +15/-15 (duck) and I have a relatively wide stance (23"). The Legacy is 159cm and the Proto is 158cm. I am 5'10" and 185lbs for reference.
2) I found snowprofessor helpful after I understood what I was doing but not before. Their explanations are good but a little wordy (jokes etc) IMO. The only thing that I found initially helpful on snowprofessor was skating and getting off the lift after I learned to slide and turn. Until you can turn don't even think about getting on the lift, no matter if there are thousands of toddlers attached to their parent units behaving like slowly moving or stopped orange highway cone obstacles randomly scattered on the bunny hill.:yahoo:
3) First thing I taught myself was just sliding down the bunny hill from toe side and then heel side. On the heel side a major thing to remember is to have the high backs of your bindings pressing against your calf (but not pushing you over forward). The reason for this is it takes virtually no effort to slide (and control the edge) on the heel side when your bindings are setup this way. At first mine were not (GNU Mutant bindings and Burton boots) and I had a hard time keeping my balance on heel side because I was leaning back. So adjust the bindings properly and adjust them with whatever you wear while riding on the mountain (your snow pants, boots geared up on a flat surface) or else the bindings could be over adjusted forward and apply too much pressure on your calf when you lock in on the mountain and you will be pushed forward on the board by the bindings (bad).
4) Once you get the sliding down (I practiced sliding both sides all the way down the bunny hill occasionally stopping and restarting the slide to allow toddler/parent units slowly moving highway cone obstacles to pass, until I could do it consistently without falling), I moved on to turns (not linking turns, just turns). Since I am goofy foot I got myself over to the left side of the bunny hill (looking down I positioned myself to the left) and on my toe side facing up the hill. Now here is the scary part and where you must do what I say next otherwise you will rocket down the hill and wreck (been there done that). As you shift the pressure on your front foot back onto the heel while leaning forward you will start to turn. Now the scary part, keep the pressure on the front foot heel AND SLOWLY AND CALMLY COUNT TO 3 (1 - 2 - 3) AND I PROMISE YOU WILL TURN.

Counting to three makes you not react to the scary part where you begin the turn and think you are going to shoot down the hill (you won't). Make sure that your knees are bent and specifically that your front knee obscures the view of your boot, if you can see your boot you are not bending your knee properly. This is how to learn the heel side turn with goofy foot. If you are regular just reverse the process and start at the right side of the bunny slope facing downhill but instead of turning on heel side, you are going to do the same thing I described above on the toe side. The main thing is continue to apply pressure and count to three to get you through the scary feeling that you are going to shoot down the hill. If you don't continue to apply pressure you will shoot down the hill. Counting to three while applying pressure overcomes your natural fear that you will not turn (you will turn using this procedure).
5) I used this procedure myself to learn how to turn on both toe and heel sides and it worked for me. Once your comfortable turning on both sides using this approach, linking the turns together is very easy because you have dealt with the issue of fear doing basic turns.
6) Once you have split turns you can move on to switch and simple tricks (spinning down the slope and other fun things).
If you can't get the 1-2-3 down and if you make it to big mountain in Whitefish Montana I will show you how to do this. I am on the mountain everyday. A little about me: I am the chief science officer of a new Biotech company in Whitefish that is developing a technology that trains immune system cells to destroy Glioblastoma (brain) cancer. Riding everyday, either in the morning or evening, clears my mind and results in focused concentration so its part of my work day. In the summer I am going to learn to long board so that I can practice snowboarding moves throughout the year.
Hope this helps and good luck learning to ride. The main thing is NEVER GIVE UP and while learning to ride NO FEAR!
One last thing about me: I never skiied or snowboarded before, ever. I got onto a deck for the first time about two weeks ago and am now linking turns and riding switch.
All the best,
BearPaw
PS: Make sure your board is waxed at the snowboard shop before learning to turn. In my experience the factory wax is worthless and hinders the learning process. I know they don't like to wax the board until the factory wax is worn off a little, but that happens fast from just practicing toe and heel side slides down the bunny hill, i.e. after the first day.