First off, the frog in the picture isn't just floating, he is dead. Dropsy is often fatal. Search google for something along the lines of "cures for dropsy in frogs" or "dropsy care in frogs" etc...
I understand how it is to be unable to take a pet the the vet. I have many animals but sadly money is tight so vets are only available to us if absolutely needed. I just recently had to have a collared lizard put down, she had MBD and was having seizures.
Let me give you some advice. Clean the water really, really well. Clean all the tank furniture. Clean the gravel. Do NOT use soap unless youre 100% able to get all of it off. USE A WATER SOFTENER! This is VERY important!
Check the temperatures. If they are too low, try to raise them. They have special heating bulbs that won't disturb their sleep paterns.
I personally lost two fire-bellied toads... One to dropsy and another from a bacterial illness. I had three, so before the third passed away I found him a new home with someone more capable. Scoop is still alive to this day. 
Do what you can for your guy. If you can't handle the problems, find a friend or someone who may know how to help. Other than the suggestions I gave you, all I can really say is this:
Love him and make him as comfortable as possible. Talk to him. I know it sounds odd, but pets will react to their owners' voices, whether it be a cat, dog, bird, or frog. 
Feel free to e-mail me at shopunke@yahoo.com and maybe I can help you out further.
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Amanda ^_^
"Animals are reliable, many full of love, true in their affections, predictable in their actions, grateful and loyal. Difficult standards for people to live up to." ~Alfred A. Montapert