After your enemy-player’s turn click on "Militia" unit. In the menu you will have a possibility to "Run & Attack" (from the right, from above, from a side) by clicking on a "Run & Attack" button. If you click on this button you will see a violet area that will show a unit’s moving distance in a "Run & Attack". If you see this sector is too close to an enemy-player click on him.
In the same way you can move to an enemy-unit. You have just to click on a "Move" button and on "Attack" button in the menu and attack. If you attack an enemy-unit with "Healer" unit move a group of units by "Healer" unit to enemy-units with the help of "Move" button. Instead of "Attack" button click on a "Heal" button and then on an enemy-unit.