Hi Alan,
did you already perform a terrain correction on the image?
If not, please be aware of the specifics of SAR acquisition geometry; Sentinel-1 is a so-called right-looking satellite acquires images in ascending and descending orbit. Depending on the current orbit from the scene, the image appears “flipped”.
You can find more information in this related post:
For more information on the technical properties, please have a look at this detailed description of the technical properties of Sentinel-1:
For more “starter information” you can also have a look here: https://saredu.dlr.de/
And here, an online course is starting next month on the topic of an “Introduction to Radar Remote Sensing”: https://eo-college.org/courses/echoes-in-space/
It may seem a little much when you’re just starting in the radar world, but just keep looking up things you don’t understand. We all started from scratch 
Welcome to the community!
Regards,
Denise