I want to start a cleaning business doing offices and homes what di I have to do first

This must be some kind of class assignment as we get this question with regularity:
https://www.askmehelpdesk.com/search.php?searchid=2850018

You formulate in your mind a business plan or write out a business plan of some kind. You also go to an insurance agent and get at least liability insurance if you are going to conducting this business by yourself. If you plan on having employees of any kind, then that would be a separate matter entirely, concerns about which you could also ask the insurance agent.

If it were me, I would gather the tools that thought I would need, print up business cards and flyers and advertise that I am providing this kind of service to whomever I might meet as well as posting my small shingle on every public bulletin board that I could find that was available to advertise such things.

I have also covered the basis concerning the insurance aspects of this for myself and in what I have posted above.

You could also do extensive advertising on the Internet for free. But, I might post about that later if you are interested in learning how to do that.