Hello, @Md_Asif_Kabir_Emon and welcome to the MongoDB community! 
Blockquote
How could I join two collections for query in mongodb ?
Well, in your case, I think $lookup stage of the aggregation pipeline is what you’re looking for.
Additionally, I’d recommend to read about data modelling in MongoDB - maybe you won’t need two collections and, therefore, merging them 
Also, it is better to format your code examples before posting. This way your topic will be easier to read and more people will be willing to help you.