Been there, done that, still finding my way out (with T2i).
I find the best way to learn is discover the situations where the Auto mode is not quite working and then see how a specific mode will help out.
Here is a couple of examples:
- In auto-mode, you don't get to chose your focal point. I found that often the camera will focus on the wrong thing. So, I switch to P(rogramme) mode and set the focus point to the center only. This means, I can quickly point the camera at the right item and take picture. More advanced version would be half-shutter and recompose or post-processing crop to fake the rule-of-thirds composition. That's all later though. Just understand that fixing your focus point allows you to control that aspect better and let's you take more pictures in-focus faster.
- I just took 400 pictures of a soccer game. Not being a professional photographer, I switched into TV (shutter priority/velocity) mode, set it to 125, ISO to 400, center focus point, no flash. Let everything else be automatic. So, I could basically point the camera at the right person/item and press the button. If the person moved fast, but not terribly fast, I would get an in-focus picture of them, but people around him/her may or may not be blurry (because aperture would change based on light available). Also, a person moving too fast would be artistically - if I say so myself - blurry for the fast part of their body. Lots of shots with blurry feet or blurry ball. People loved it.
- Similarly, I was trying to do macro shots and create shallow depth of field effect. So, I switched to AV (Aperture Priority/Velocity) and set it to the smallest number I could get (3.5 unfortunately). Then, I took pictures with Auto ISO or with 200 ISO and did not care about shutter speed (the flower did not run). Have some nice shots - again, in my own opinion - there.
So, just think about those situations and practice this basic just-out-of-the-box options. After a while, you will start to get the feel for what the different settings and values really do and then you can get to the next step.
Finally, I was really afraid of the M(anual) mode, as I did not think I knew enough to even bother. Then, I actually switched into it and realized that there is an indicator at the bottom that shows you whether the camera thinks your picture will be under or over exposed for the particular setting of ISO/shutter/aperture. Just having that floating indicator and seeing it going back and forth as I change random settings was liberating and also instructional. I have a wide-range lens and only while doing the zoom in the manual mode I realized that the most open aperture (3.5) is only available when I am NOT zoomed in. As I zoom in, it rapidly closes to start at 4.5 and even 5.5 (I think). Doh! But now that I understand that, if the picture is too dark, I will unzoom and get more close to the subject.
I still don't use manual mode much at all (takes too long to set it all up). But I am starting to see the situations when it would become useful.