Q: How do I write the background of a research in a historical and descriptive way?

I am not entirely sure what you mean by “historical and descriptive.” I think you wish to understand how to set the context for your topic by narrating what has been done so far in the field, starting with old research and then gradually, in a chronological order, arriving at more recent work in the field.  

The background is the first part of the introduction and has to set the context for the research. So, you need to talk about the existing research in the area and the gaps in this research. Based on this, the background has to lead to the purpose of the research and thus talk about the goals of the research. Therefore, in your case, you could discuss what the existing research says about various strategies to promote small business and how effective (or not) these have been. You could start with some of the pioneering studies in the field of small businesses. You could discuss the various strategies chronologically and describe the effectiveness of each strategy. It would also help to discuss the effectiveness of various strategies using relevant statistics. For more information, you may refer to the following sources:

• How to write the background of your study
• 8 Dos and 8 don'ts of writing an engaging study background
• How to write the background to the study in a research paper?