How do i setup a 10 gallon red clawed crab habitat?

I know they are brackish. How do i make brackish water and how much water should i use and how do i setup the habitat with a 10 gallon tank? Should i use sand or gravel? Do i need iodine so they can molt properly and how much iodine? Should i use a filter and if so which one? Do i need a water heater? What light do i need? How much land should i make? Am i missing anything else? Answers will be appreciated! Also please answer quick thinking about getting them this week!