First you need to design your gRNA, there are several online tools to help you with that (eg. https://horizondiscovery.com/en/ordering-and-calculation-tools/crispr-design-tool). You then co-transfect your organism with the gRNA and either a plasmid that expresses Cas9 or mRNA for Cas9 translation. Although optional you can also co-transfect with an oligo that has a selective marker flanked by 300bp homology arms so you can knock the selective marker into your cut site. This allows for easier screening of transformants.

Hi Agida,

Please elaborate on your question. What is your rationale for using CRISPR-Cas9? Are you planning to use it for gene knock-in/out or for interference? what is your host? The basic rule is to design a guide sequence against your gene of interest, clone it to a vector, transfect it to the host along with the cas9. There could different ways to deliver the gRNA-Cas9 complexes.

Ok, thanks so much for your time and responds. I will be doing knock out but I dont know the principles and steps involve