You should return those fish to the store immediately or they will die. There are alot of issues with what you've posted and I'm not sure where to start. Ugh.
First off a 10 gallon tank is not even appropriate for one angel fish - it is way too small. Do some research on "angel fish care".
Another issue is that you did not prepare your tank for fish. Do some research on the "Nitrogen cycle" - this is a process that grows bacteria in your tank and filter that will turn the fish waste, which is toxic to them and will kill them, into a less harmful substance that can be removed with weekly water changes. This process typically takes 6-8 weeks. Right now your fish are being poisoned by the water that they are in, and it will kill them quickly. Just because the water looks clear does not mean that it is suitable for fish. The ammonia, nitrite and nitrate that builds up in the tank are clear and odorless. Dumping a bunch of food in will add to this problem as it produces more ammonia as it sits in the tank and rots. Read the food label - it probably says to feed only as much as they will eat in 3 minutes. But in any event your fish are sick and eating is the last thing they want to do, so stop dumping food in.
Return the fish asap and then sit down at your computer and do alot of research before buying more. You will never be able to keep angels in a 10 gallon tank, but there are lots of smaller fish you could keep. Research the nitrogen cycle first, then research things like water conditioners, temperature for a tropical fish tank, basic fish care, fish appropriate for a 10 gallon tank, etc. Honestly, if you saved up for a year to buy a tank then you should have been doing this research during that time instead of waiting until after you buy the fish.
And speaking of temp and water conditioner - did you treat the water with a conditioner before adding the fish? And what is the actual temp of the tank? What type of filter are you running?
Also, please don't drink the aquarium water.