Next in importance after the honourable ordinaries are the sub-ordinaries. The sub-ordinaries are variations of the honourable ordinaries and were invented because so many different shields were needed it would have not been possible if only the limited number of honourable ordinaries were used.
Each of the honourable ordinaries has their own variations.

Latin

Patriarchal

Pointed

Maltese

Potent

Formy

Crosslet

Crosslet Fitched

Pommel

Calvary
These are a few of the sub-ordinaries of the cross. There are many more but all of these can be used in the shield designer. See below.

Quarterly sable and gules a
maltese cross or

Argent a cross crosslet gules
Roundels are discs and they have different names depending on their colour. The colours and names are shown below. Normally the bezants (gold), plates (silver) and fountains (blue and white wavy lines) should be drawn flat while the other roundels are shaded to give them a spherical shape. The current version on the shield designer does not do this.

Bezant

Plate

Torteau

Hurt

Pomme

Golpe

Pellet

Fountain

Argent on a fess gules between
three pellets three fountains.

Azure on a bend or three torteaus
You can choose to add one of the additional divisions shown above to your shield. These can be found on the 'Set Field Division' popup. At the bottom of the popup is a 'More' button that will give you these extra division styles.
Blazon
More sections will be added at a later date. I hope this has given you a good introduction to heraldry.

A: Dexter Chief
B: Middle Chief
C: Sinister Chief
D: Honour Point
E: Fess-point (middle of shield)
F: Nombril / Naval point
G: Dexter Base
H: Middle Base
I: Sinister Base