I make my own bread all the time. All though I haven't made sourdough bread because I don't really like it, I buy all of my products from
King Arthur Flour - Try it Once, Trust it Always On their website you can shop for products and buy a starter and all the bread making products you can think of. You will also find many recipes and some will have photos (if you see the word blog-hit that for photos) and I have found that useful for a visual on what my dough should look like.
Also, I only use instant yeast which I buy from King Arthur. It is so much easier.
Good luck!