You'll need to get a gooseneck style lamp and a 6500K rated florescent bulb and run the light during normal daytime hours. There is no real need to feed the plant.

If you do decide to add bugs to the diet, it doesn't have to be just flies.

Various insects and arachnids would be OK, as long as it is about 1/3 the size of the traps. If you have the option, then try not to give insects with hard shells. They would take some trial and error to see what your VFT can handle. Otherwise, some soft-bodies insects would be OK.

if you're gonna feed it, make sure whatever you feed it is still alive enough to move. The movement the insect makes is what prompts the trap to shut tighter; otherwise it'll open up slowly and the plant won't take in the nutrients from it. About the light, VFT loves sun. I had one back in Puerto Rico and it was dying due to the low light conditions, but that's because I had it inside my room and away from all the windows. Does any sun come in trough that window you have it in? Mine started flowering after I set it out in the full sun.