The answer to this objective is in bold face in the next two paragraphs:

A fold structure is just a description of how the primary and secondary structure folds in on itself. If you looked at 100 proteins, you would see that there are many different ways that the primary and secondary structure folded to make the tertiary structure. For a protein or for groups of proteins, a fold is a description of the relative orientation of the secondary structure making up the tertiary structure.
A fold family is a group of proteins that are clearly related to each other by evolution. The genes for these proteins evolved from the same gene. The gene was duplicated, maybe a number of times, and each gene was changed by a series of mutations. In the end, a number of different proteins with similar structures were formed.
The reason I mention "fold structure or protein fold" above is to make you aware that the term fold is used in many different ways in protein chemistry. When you see the term fold dont jump to any conclusions. When you see the term "fold family," do jump to conclusions. the proteins in it are related.

Below, I have expanded the above explanation but, if you can answer the practice problems, you will be able to answer related problems on the final.

Structural Classification of Proteins (SCOP) is a database in which proteins have been classified according to their structural and evolutionary relationships.

The hierarchy of the database is Class, Fold, Superfamily, Family

Class: general "structural architecture" of the domain.  Three major classes are recognized; mainly-alpha helix, mainly-beta strands and alpha-beta strands.  A fourth class is also identified which contains protein domains which have low secondary structure content.
Fold: Major structural similarity-Proteins are defined as having a common fold if they have the same major secondary structures in the same arrangement and with the same topological connections. Different proteins with the same fold often have peripheral elements of secondary structure and turn regions that differ in size and conformation. In some cases, these differing peripheral regions may comprise half the structure. Proteins placed together in the same fold category may not have a common evolutionary origin: the structural similarities could arise just from the physics and chemistry of proteins favoring certain packing arrangements and chain topologies.
Superfamily: Probable common evolutionary origin-Proteins that have low sequence identities, but whose structural and functional features suggest that a common evolutionary origin is probable are placed together in superfamilies. For example, actin, the ATPase domain of the heat shock protein, and hexokinase form a superfamily
(Fold) Family: Clear evolutionarily relationship-Proteins clustered together into families are clearly evolutionarily related. Generally, this means that pairwise residue identities between the proteins are 30% and greater. However, in some cases similar functions and structures provide definitive evidence of common descent in the absence of high sequence identity; for example, many globins form a family though some members have sequence identities of only 15%.