OK, these are great tips! Thanks so much! I think I was just spending too much time figuring out where the allele is, in the overall picture. I was focusing on how many and where, etc. So, now I am this far:
A gene is a piece of DNA that carries information about a specific trait.
A chromosome is a string of genes connected together (although most of the chromosome is DNA that has no known function or no genetic activity).
An allele is a gene that is a member of a set of genes that all belong to the same locus, or location, on a chromosome. These genes are often thought of as being related to each other through mutations (one allele could be a mutation of another allele) or they could be mutations of an ancestor gene.
Chickens, like people, usually have two of every chromosome. The chromosomes in a chromosome pair are not identical, since one comes from each parent. A gene is said to be dominant when only one gene (rather than two) is sufficient for the expression of that trait to which the gene corresponds. Some genes are referred to as incompletely dominant. The expression of these genes is inhibited by (usually unknown) modifying genes. When the inhibiting, modifying genes are not present, the incompletely dominant gene expresses. This interaction with modifying genes is responsible for the seemingly random nature of the expression of incompletely dominant genes.