LLM finetune

Hi Team,

I am using the LLama2, given by ollama.ai.
Using a data set which is in json format and have key value pair, in which key is the term of 2 words and value is the explanation of that term.
Although, I need to make a tool term explanation.
In this tool , user can input his term and we need provide a explanation is exist.

Q1. Do i need to write a prompt ? If i am writing a prompt it works some time and some time not. And it will generate a own definition if term not exist.

Kindly help how should i approach to this !!