"all the bits and pieces start to fit" who will do me a favo

"all the bits and pieces start to fit" who will do me a favor?
what it's the meaning of that sentence i posted,i don't even know how to use this sentence yet.i will probably use it in the wrong place if you guys do not help me correct me.
by the way,i will probably use it in the wrong place if you guys do not help me correct me.& if you guys do not help me correct me i will probably use it in the wrong place .which of these two sentence is right.