***Looking for some advice here please as I'm pretty non-existent when it comes to electronics. I want to use a mixer to 'blend' backing tracks with my guitar then send that to my amp.
You can definitely do this. You will get the blended sound amplified by your amp, along with whatever tonal characteristics your guitar amp provides.
I definitely would not do it. Because the sound coming out is very unlikely to be something that would sound good (to me - your opinion may vary):
Guitar amplifier input stages do not amplify sound cleanly like a PA would - they are not meant to. They are meant to be part of the sound of the guitar, so there are distortions, non-linear bits, overdriven bits etc. Which means what you get out is not like having a guitar sound and a backing sound - it will be almost certainly not blend like you imagine.
- get a PA of some kind for your backing to keep it away from your guitar gain stage, or
- insert your mixer in the FX return on your amp so it just goes to the power stage
***Thanks for your input, guys. First, here's what I hope to be able to do: Mix a backing track/sound track from laptop (or other source) with my pedal steel (pedal steel > volume pedal > mixer) then from mixer to my amp as I can get the benefit of amp effects (mainly reverb). Then, the mixed sound will either come through the amp's speaker, or if I'm trying to stay friendly with my neighbours, through my headphones via the H/phone output in the back of the amp.
Now, here's where I'm at. (I'm also posting this as it may be helpful to anyone else who is trying for something similar.) I have a borrowed Yamaha mixer and tried a few things with that. I first tried going from pedal steel to volume pedal to amp then from there into Line In on mixer -- that didn't work -- no sound whatsoever. I then tried volume pedal into Line In on mixer then from C-R Out(L) on mixer to amp -- still nothing.
I've posted a photo of what I did that eventually worked for me.
The yellow lead is from volume pedal; the 2 phono plugs into "2TR In" are from laptop and the black lead from "Phones" goes to my amp.