How to clean this single hung window

I have a window that desperately needs cleaning

I believe it is a single hung window as it appears there’s no way to open the upper part. The window doesn’t appear to tilt in any way. I checked around the window it doesn’t appear to have a manufacturer name or model name that I could look up.

I don’t know how to reach the part that needs cleaning. On both side, there are this string going up:

On one side, I noticed a screw:

Other than that I didn’t find any trigger or any hardware that appear to be “interact-able”

How should I go about this?