Comment /sticky note in library

Hello. This is my first post in the forum.

As I am building my library in End Note, I am having difficulties keeping track of the reasons I included the references and need a system that enables me to quickly give me some information. I know I can add a sticky note in the start of an article/attachments, however It’s quite cumbersome to open the attachments when i just need a quick overview… In addition, some articles/references I only have in paper, or missing/haven’t found yet all together.

However, I just need an simple or efficient way to enter a comment to the reference, nothing fancy.

Any suggestions?