>>2436887Forgot pic. It's super easy, just scape into a little jar or something with some water and leave it a few days to start looking gross then gently rinse untill it's just seeds and let dry.
And you can successfully save seeds from grocery store tomatoes or other things, just know you won't always get what you expected. These are the seeds from my favorite cherry tomato which originally came from a store and now I save them to keep growing.