Take a screenshot like this. 
You can drag and drop images after making a few posts. Welcome to the forum BTW. 
PS It is possible that it is an issue with @partha’s package. I am not sure but I will ping him. In any case, it is a good idea to use 2.9.0 release instead of 2.9.0-pre, which seems to be what Partha packaged judging from his screenshots.