The use of the "Inverted Minor" comes into play when your partner opens 1 of a minor and you are holding a minimum of 4 of his suit and no four card major.   The standard approach with a weak hand is to bid 2 of his suit.   However, a 2-level bid has very little effect in a competitive auction. So, using Inverted Minors with a decent but not game forcing hand a bid of 3 of his minor shows weakness and length in the specified minor. With 10+ points and a decent hand the responder would bid 2 of the minor. This (inversion) of the bid is a one round force.
       Note: with a balanced 10 and only four of the minor often it is safer to just bid 1NT

Rebids by Opener  When partner bids 3 of the minor (inverted) he is showing weakness and 6-9 points, so in most cases the opener will pass unless he has great strength. On the other hand a bid of 2 of the minor is a one round force. At this point responder has not limited his hand. A bid of 2nt shows a balanced hand with probably only 3 cards in the designated minor. A bid of 3 of the minor is fairly weak and shows the desire to play in that suit. Any other bid shows extra values leaving it up to responder to further pursue the game potential of the hand.