Need help "fixing" my chain (on sprockets) properly....

Bykenewbie

Ok,
I am a complete bike newbie, I knwo nothing about bikes - beyond riding one!
Ok here is the situation: I have a 24-speed Kona mountain bike. I have the left shifter on #2 and the right shifter on #8 (the "hardest", #1 being "easiest"). When I switched from #7 up to #8 it would keep "slipping" on #8 and not "catch" for lack of a better word. Anyway there was a lot of gunk and dirt on the chain and gears (sprockets? Those things with teeth on them). I degreased and cleaned it all, then lubed up the chain and teeth. The slipping seems to be ok.
My problem is this: with the right shifter still on #8 the chain placement on the gears seems wrong, it is "aligned" with the front part of the chain on the big front cog and the rear part also on the biggest rear cog. So the chain is simply aligned straight. But this does not seem right.

1) How should I place the chain properly? I have ride it next week and right now cannot affor dot take it to a shop.

2) If I "fix" gear#8, will #1-7 also fall into place properly?

Any help appreciated, I tried explain it as best as my limited knowledsge will allow!

bykenewbie