1st off let me say welcome to Roadfood!
For a soup it’s going to be very easy. 1st decide what kind, with this broth you could easily do a vegetable or a legume soup. Take your favorite vegetables, potato, carrot, turnips, or even cauliflower and broccoli. Basically whatever.
Chop veggies into approx. 1/2 inch size for potatoes or 1/8 slice for carrots. Put into boiling broth and then turn down to a simmer until tender.
For leguems, beans/peas, rinse with cold water in a colander to wash off any dirt. Some people recommend a soak in for for a few to several hours. I don’t. Put beans into boiling broth and then simmer for 2 – 4 hours. Again until tender. The time is going to depend on what bean/pea you used.
You are going to have plenty of salt in this broth already so I sure wouldn’t add any to start with. Add some pepper and a bit of garlic I always add some onion to most of mine.
Feel free to ask more ?s if ya have them.