Ok, for starters you need a hero do anything on the Aragon servers. So if you want to move troops, you need to make sure a hero is with them.

So below are the steps to move an army from one city to another:
i) click on attack under the map tab
ii) select all of your troops plus the hero
iii) Select the "AID" action
iv) Make sure the correct city is the target
v) send away

The produced troops moving to a single city is due to a rally point that you have built. Destroy the rally point and armies that are built in city respective will stay in that same city. The rally point is good for boosting troops in a city if you are under attack or just need a bigger army where your hero is.

Your last question is answered with the "AID" option, you can't have "ATTACK" selected when targeting your own towns.

Good luck and I hope things work out