I'm *very* new with Inkscape; I only downloaded it yesterday. But I'm very computer literate and I'm getting the hang of it.
I have one problem I haven't been able to figure out though. I can't make a layer simply overlap another.

Like so. The armbands are one layer, the wing another layer, but when they're both visible the armbands become opaque, but the opacity is set to 100%.
Is there anyway to make it actually 100% opaque?

tool, in which case clicking on the stop handles would have shown translucent colours in the fill swatch at the bottom left, which you could make opaque from the right-click context menu.