>>First: I don’t really know how to use Illustrator
That’s a problem right there.
Well, I don’t remember what CS have – since that’s a tad old, but maybe this workflow remained the same (I’m on CS4 and CS5). Anyhow…
1. First ungroup all groups. You may have to repeat the Ungroup command a couple of times depending on how they are grouped. If there are elements that you DO NOT want to have separate layers assigned in PS, then do not ungroup those.
2. Click/select (hilite) the very topmost layer.
3. In the Layer’s palette popup menu select “Release to Layers (Sequence)”. This will group every individual object/shape into a group. And every group will be a separate layer in PS.
4. Now File > Export > PSD
Now you should have each item/element that was in a group on a separate layer.