Consolidation of Storage Space

Hello,

I have a PowerEdge T420 server running Windows server 2008 R2 with all the HW & SW updates to date, however, we changed what we store on the server and thus have several drives on it which are sparsely occupied. We want to CONSOLIDATE all these drives into one large drive or volume. 

Can anyone point me to some links containing the pertinent instructions?

Thanks,