Here's a great resource from the University of Missouri Extension that has detailed pictures of various strawberry diseases to help with disease identification. It's a PDF file.
Once you've successfully identified the problem, you can then search the internet for products that may be able to treat the disease. For example, if you have strawberry leaf spot, search for "strawberry leaf spot treatment" and see what you get. You want to look for the product label (usually a PDF) and go to the crop you want to treat and see if your problem is listed. If the disease you suspect is not listed on the label, you should look for other products because it is likely the product you've found is not effective against that particular pathogen.
Information about Strawberry Verticillium Wilt: