I always make stock (broth) rather than buy it in a box from the supermarket. Those stocks have too much sodium for my liking, even the low-sodium types. So many recipes list either vegetable, chicken or beef stock as an ingredient, but if you don't have any on hand you might just use water and hope for the best. The recipe ends up being thin, watery and flavorless.
I don't add salt to any of my stocks.
Salt can be added during cooking when you're preparing a recipe using your previously made stock (broth).
You'll need a wire strainer for sure!
Vegetable Stock (I would omit the salt)
A crockpot is a great tool for this job. Just put everything in it then let it simmer.
I usually freeze stocks in small plastic containers and ice cube trays. When the cubes are frozen I put them in a freezer bag. With this method of freezing, I can take out as much or as little as I need.