Anil, it works the same way as any natural broad targeting transcriptional activator will work. It is a fusion of dCas9 and activation domain(s) from viral and eukaryotic transcriptional activators. dCas9 part target promoter area of a target gene through specific sgRNA ( it is better to have multiple binding >1 sgRNA) and brings activator domain(s) to that gene promoter area. Than, usual pattern of gene activation follows.

Thank you