How do you make an offering to a spirit for continuous blessings and how do you know that they have accepted the offering.

You don't,

There are no "entities" that people describe as spirits... in fact, there is no proven supernatural... imps, devils, god, gods, satans, tooth fairies, and so on. The supernatural is an ancient construct that illiterate, frightened human beings used to explan the workings of the natural world to themselves in order to alleviate fear... today, we have facts and knowledge that explain how much of the *natural world* world.

Enjoy Real Life!!