I hadn't heard of YessNet until you mentioned them in this post but they mainly find promotional/tradeshow work for models. They are not a modeling agency, though. They are an online company that basically contains a database of models and promotional talent so that models can connect with agencies and clients hoping to hire them for projects. They do offer a lot of cool things for their models, though so if you are into promotional and tradeshow work then you should look into it. But that aside, they are not a modeling agency so even if you end up getting work through them, you should still try to pursue finding agency representation.
But so far YessNet seems like a cool way to get yourself out there and to begin working and getting paid.