You can design and setup your Aquarium easy y some steps:
you need Tank , Filter, Heater, Lid, Light, Gravel
lest start now ;)
you need 10 or 15 pound of Gravel , and put in the bottom of your tank before add water. after that you need some decoration like: Rocks, Planet decoration. You can find more decoration in the pet store. now you have to add your decoration before add water.
Add the Gravels and then put your decoration how do you like that! and after that need to add water, in order to do not destroyed Gravels and you design put the plate on the gravels and add water on under plate slowly. next you need cover the tank and put the door of the tank. Finally add your Filter and Heater to the tank . and now your freshwater aquarium is done ! Enjoy to watch your Fish ;)