The rules often call upon a player to make tests or actions at the start of a turn. These are mostly (as discussed in the section), or special rules that apply to a specific race, such as the Animosity rule for Orcs & Goblins (described in the relevant Armies book).
During the movement phase you may move your models as defined in the rules for movement.
In the magic phase your Wizards may cast spells. The full rules for spellcasting and magic are described at the end of the rules section - they are quite advanced and not needed right from the start.
During the shooting phase you may fire any missile weapons as described in the rules for shooting.
During the close combat phase all troops in close combat fight. This is an exception to the normal turn sequence in that both sides fight, not just the side whose turn it is.