Ok here I go;
1. You are attacking them not the creature unless a spell of effect makes you do so. So this is the scenario; "i'll attack you for 2 (because your creature is a 2/2)." then the opponent says; "ok i'll block your 2/2 with my 3/3" your creature dies and their's lives.
2. Reiterating the number one, no matter what the enemy plays, THEY are always your intended target. Your spells are used to clear the way for this to happen.
3. Some enchantments called AURAS are able to attach to other creatures or enchant whatever target it specifies on the card itself. ARTIFACTS can EQUIP themselves to only your creatures and once equipped can be passed to another creature just by paying the equip cost again. Remember, if it does not say that the opponent is a target in the CARD TEXT then they CANNOT be target by that spell.
4. I'm going to play out htis move for you step by step so make sure you pay careful attention;
a) Your opponent (the attacker) cast
enfeeblement on your 6/6 so it actually becomes a 6/4 not a 6/2.
b) He swings (attacks) with his 3/3 and 3/1 (which means if you don't block it you'll be taking 6 points of damage). Unless your creature specifically says or you gave it the effect, it can only block ONE creature, but if you have multiple creatures (which you didn't specify) then you could have multiple creatures block the same single attacking creature if you wanted. This is what some people call "double blocking", "triple blocking", etc.
c) You choose which single creature to block because you only have one creature. Preferably you'd want to block his 3/3 with your 6/4. This way you'd only take 3 points of damage this turn, you would have killed off his stronger creature just by defending, and your creature would survive the turn with at least one point of toughness remaining (because it would be a 6/1 before the turn is over). No more moves end turn.
d) Play
plague witch from your hand and use her effect on your opponent's remaining creature. Because it's toughness will be reduced to ZERO or LESS then it would automatically die (and that is a STAT REDUCTION NOT DAMAGE, it's a nice little loophole to know for later games). Now that your opponent's only creature is
gone you can swing for 6 damage unblocked and still have your
plague witch as a defender for next turn (if your opponent plays a creature that has HASTE, meaning it can attack the turn it's summoned).
These are the kind of plays that you'd want to make in that kind of situation. If you can't remove the enchantment then play
kheru bloodsucker and sacrifice your 6/4 enchanted creature. Both of the effects will activate, your opponent will lose 2 and you'll gain 2, and if you play
ghoulcaller's chant you can return it right back to your hand to replay that creature. See the cool things you can do when you plan out your plays?