With BlueStacks you download and run the app player, install the traditional verssion of the Instagram App grom the Google Play Store and run things just like you woould from your phone. You can drag and drop videos and pictures from your dekstop. Even add your text, audio or stickers just like you would normally do on your phone.
I'm working on a quick how to and tutorial from more info. For now though I recommened trying it out and posting any questions in the comments below!