Yes 
You can do that in many ways, the most common would be by clicking the castle you wish to move troops to, then pressing "station". Once done that a screen will appear and you can select what castle you wish to move from. The press the green button then you can choose what troops you want to move, if you press, "autofill" it will only choose defenders and fill it up, if you want to move attack troops you will need to do click on the troop like in an attack.
Or the same process but instead of clicking on your castle you go into the "economy" to "overview" to "military overview" and press the station button located just next to the scroll bar on the left (far right of the screen if you don't have the scroll bar)
Once level18 (or 25) you can unlock kingdoms, you can move troops through the kingdoms, but you cannot move them into your outposts from other kingdoms, only from. It is a similar process if you need an explanation (once you have it) please ask
The autofill option only appears when you are sending troops to another alliance member