As for a mace of spell storing -- very simple. Open up your character, go to the Purchase screen, below the window displaying the items you can buy is a button marked New. Click it, and you'll be taken to the place where you can put together magic items per the DMG tables. Select Weapon, Melee. Select Mace, select its enhancement bonus (+1 to +5), and then from the properties below select Spell Storing. Click OK, then from the list of magic weapons that appears select the mace you just made and purchase it (or "buy for free").