Down in the right hand corner of your screen there will be a little bag icon next to the cogs. Click this and then click on cash warehouse. The lowest line should have all the items that you can obtain. Right click them to put them into your inventory. Your inventory must have at least one empty space per item. If you get a gift box after reaching certain levels; 10, 20, 30, etc. then you must have enough slots to account for all the items in the gift box if you so wish to open them. For the easter event going on now, after obtaining the easter coin you must go over to Sayakomon in the Dats center where you can use the coins to buy items from it.