The Hold Control Panel (HCP) is located inside the FMS Route panel.  The HCP is used to follow holding clearances issued by the Air Traffic Controller.  Consistent with the other Flight Deck Controls, the fields in the HCP use the same color scheme.  For the HCP, the white parameters can be published holding patterns, or specified but unengaged (pre-selected) parameters.

To enter into a holding pattern, from the HCP click on the "FIX" button to bring up a drop-down menu of available fixes.  When you select a fix from the list, it will display in the fix field of the HCP in white.  If the selected fix has a published holding patter, the parameters for the holding pattern will be displayed in white.  You can also use your keyboard to directly type in this field.

Clicking the "ALT" button will display a list of altitudes, or flight levels for your holding pattern.  Similar to other altitude menus, the different flight levels are divided into two groupings: "High" and "Low."  When you select an altitude from the list, it will display in the altitude field of the HCP in white.  You can also use your keyboard to directly type in this field.

If you click the "SPD" button, a drop-down menu will appear, listing different speeds (in knots) to use for your holding pattern.  When you select a speed from the list, it will display in the speed field of the HCP in white.  You can also use your keyboard to directly type in this field.

Clicking the "TURN: button will display the turn direction options for your holding pattern.  Selecting "NONE" will result in your aircraft following the published turning direction.  When you select a direction from the list, it will display in the speed field of the HCP in white.  You can also use your keyboard to directly type in this field.

At this point, all the parameters of your holding pattern are still inactive, meaning they haven't been activated, the equivalent of an "execute" from the FMS.  Once the holding parameters are correct, click the "Engage" button to activate the hold.  This will cause the parameters to turn magenta, and will change the engage button to display "Disengage."  This also indicates the holding pattern is updated in your FMS.  When you want to exit the holding pattern, all you need to do is click the disengage button.  Your aircraft's FMS will automatically put you back on the previous routing.