Starter tank help

[SleepyPirate]

Just started a 90 gallon tank, so far I have a Fluval 405 filter, stock floresent light and 48x18 1/2x23 " tank with a few accesories heater/underwater fan. So far all I have is live sand about 1" all around. I think my lighting is totaly inadequite for anything more so im afraid to upgrade I relise I need a sump in the future but as of now cant afford. Does anyone have any tips on moving on up to put live rock and keep a healthy eviroment for perhaps some coral without the use of a sump?

The tank has scratchs so really i dont want this to be my future tank just a starter tank that I can transfer my healthy coral into a better tank

The live sand was bought used from a previous owner who mainly has fish but with lots of live rock so it already has a few inhabitants like snails in it.