Wow wow wow, let's let the chap walk before he can run!
no condecention intended Ian
They are right, raw shooting will help, but it does assume an desire to spend some time in front of the computer processing the images etc ... And some knowledge of processing etc!
For the sake of the argument, I'm going to assume full newbie status for you Ian, so if I cover any ground you already know please excuse me!
The compo you obviously have an eye for! Which is really all you need ... Everything else above and beyond that is just honing!
As for dynamic range...
Your camera (all cameras) are limited in the amount of difference between dark and light
This is apparent in a few of your images where instead of there being detail there is either pure white or pure black
We would call this clipped (or blown) highlight or lost shadow respectively!
Don't be disheartened! This happens to all of us! The are a variety of methods for getting around this, some basic some more advanced!
The more advanced are more effective, but getting to grips with the basic ones is part of te curve is part of the curve to the more advanced!
Basic ones
Framing
When you frame an image, look for possible areas of issue
Some of your photos have no problems, these are the ones where there is no bight sunlight shining on white water near dark rocks! Avoid that circumstance ... Avoid the situation where a "problem" may occur!
Exposure compensation
Clipped highlights are more distracting on the eye than lost shadows. So try under exposing slightly with your exposure compensation control!
Bracketing
Same as above really, bracketing is a method that will make the camera take three or more exposures on sequence at slightly different levels of exposure. This means you can just snap away 3 (or more shots) for each photo and look at them on the computer later and decide what is best!
More advanced
Grad filters
For scenes different to these, ie sky at the top land at the bottom, you can get filters to go on the front of the lens that are dark at the top and transparent at the bottom! I'm sure you can imaging why that might help in some circumstances ... Not so much for waterfalls!
Post process
Post process ie editin the photos on the computer after ... Often in combo with some of the above will reap the best results ... Especially if you shoot raw!
Raw has its benefits... Larrys explanation in Petes link is pretty good, but loosely speaking... And perhaps in terms that may sit well with you...
Edit a jpeg on the computer and it's like trying to squeeze better quality out of an 320kpbs mp3 ... The quality is there, no doubt, but of you don't like the compression the engineer used when the track was mastered, your stuck with it!
Shooting raw is like having the studio master to play with!
It is the uncompressed master version!
You just need to have the right kit to play it!
Photoshop, Lightroom, aperture ... Loads of software to choose from, most will recognise your raw files!
If you want to experiment, set the camera to shoot raw and jpeg at the same time...
If you can justify it at this stage, Lightroom is the easiest software I know!
In there you can just slide a slider to drop exposure and regain lost highlights!
Very advanced
After you have got to grips with software a bit, you can start to look at combining different exposures of te same scene... This will increase the potential dynamic range of the camera!
This method is known as HDR or (as I learnt recently) effusion!
I used it on a job on Monday for some tricky scenes, keeps you eyes peeled and I will be posting some examples soon!
If you need any help with the camera settings mentioned ... One of the canon folk will help if you ask!
Hope that helps!
Finally, as I said, please don't be disheartened by all the comments regarding this, we are trying to help, but often (and I'm as guilty of this as anyone else, I'm not haveing a dig) some of the more experienced of us forget what previous parts of the learning curve were like! It might seem daunting, but really we are here to help/advise as much as possible!
Photography is a never ending curve and we are all on it at different places!