First, recall that a a charging unit cannot turn or change formation. This is because the troops are running or galloping once the charge has begun, and would be unable to execute delicate maneuvers even if they could hear the orders of their leaders above the shouting and din. A charge is made straight towards the declared enemy target with the intention of getting as many models into combat as possible.
A unit can wheel once at the start of the charge in order to bring as many models to face the enemy as it can. If the chargers would not otherwise hit their target were they to move straight forward, then they must wheel to face their enemy, and must endeavour to bring as many models as possible into combat.
If chargers need to wheel towards their target, execute the wheel as already described measuring the distance wheeled as you normally would. This distance counts as part of the total distance charged. For example, if a unit can charge 12" it might wheel 4" to bring models to face the enemy and then move up to 8" towards them.
Once a unit has completed any required wheel it is moved straight forward towards the enemy and stops as soon as the two units touch.
Once the charging unit is in contact it is automatically align the two units so that the maximum amount of figures in the front rank are in base to base contact This extra alignment move is free so long as it does not take the unit into difficult terrain or over an obstacle it has not already crossed.
If it is impractical to align a unit properly because of interposing terrain, other models, or other factors, then it is acceptable to re-align the charged unit as well (or instead) so that the battle lines remain neat.
It can happen that a situation is confusing because of interposing terrain or models which make it impossible to align the whole unit.