How do you save a table to a data store?

I'm disappointed by the lack of example code ROBLOX put on the wiki for DataStores, and I need to find out how to do this properly.

This completely depends on how you want to save it. Also, your question doesn't make it quite clear which part you do not understand! Here's some example code.

table = {"Entry1","Entry2","Entry3"} -- This is the table we will be saving.
ds = game:GetService("DataStoreService"):GetDataStore("NameOfDatastore") -- allows us to use datastore specific methods. you can add a scope if you want.

for index,value in pairs (table) do
	ds:UpdateAsync(index, function() return value end) -- index will be our 
end 

This will save it to a datastore. You can read it out by using :GetOrderedDataStore("NameOfDatastore") but that's a different question ;)

the script may contain error

local table = {a = "0",b = "0"} -- The main table
local ds = game:GetService("DataStoreService") -- datastore service
local hs = game.HttpService -- the http service
local nds = ds:GetDataStore("test")
local value = hs:JSONDecode(nds)
if value == nil then -- if it the first time you start the game then you start with the main table
	value = table
else
	value.a = value.a + 1 --we want to add 1 to a every time
	value.b = value.b + 2 --we want to add 2 to b every time
end
local encode = hs:JSONEncode(value)
hs:SetAsync("test",encode) -- may be it (encode,"test")