Ordering your galleries
Using WordPress’ built in sorting method, it is very easy to put galleries in the order you want. Simply edit a gallery and enter a numerical value for the Order field (see below).
When you create a new gallery, the default Order value is 0, making it first.
We recommend using order values in increments of 10 (ie, 10, 20, 30, 40) instead of increments of 1 (ie, 1, 2, 3, 4). Doing so will let you put a new gallery between two existing galleries without editing the Order value on every gallery (ie, 10, 20, 25, 30, 40 where 25 would be your new gallery).