The Toad Tryout in this instance is the editing of the code from one of your website pages of your site in order to satisfy this standard. From that point on you may wish to proceed on your own, having seen the types of code changes that Toad has shown you. Alternatively you may wish to have Toad tackle the rest of the pages for you - which may, or may not, be chargeable, depending on the work involved.
You will then be able to put the coveted WC3 icon on your site to reassure visitors that you take a professional approach to the work that you do - down to the smallest detail. It is possible to do this for certain types of blogs too - depending on how accessible the code is.