Relationship between DNA strands and mRNA
I would add this as a comment to your question but do not have enough reputation. A simple look at Wikipedia (which is a very good source for general questions like these) would have provided you with an answer. I just did this to see how long it would take if I did not know the answer. It was about 20-30 seconds.

Protein synthesis: Transcription


  In transcription an mRNA chain is generated, with one strand of the DNA double helix in the genome as a template. This strand is called the template strand. 


Template strand


  Only one of the two DNA strands serve as a template for transcription. The antisense strand of DNA is read by RNA polymerase from the 3' end to the 5' end during transcription (3' → 5'). 


If I understand your confusion correctly, you also do not understand how the seemingly "non-coding" strand can be the "coding" one which seems to be a paradox. If this describes your confusion adequately you have to think of the semi-conservative replication of DNA. The "non-coding"/antisense strand is transcribed by the RNA polymerase into its complementary RNA sequence. As this sequence is complementary to the "non-coding" DNA strand, the mRNA sequence is identical (with U replacing T) to the "coding"/sense DNA strand.