Yeah, I remember being confused about these things as well. It is easier to show with visuals, but I will try to explain things with text.
Everytime you see an "X" it is a duplicated chromosome. Therefore, it counts as *two* chromosomes that are connected together in the middle. A single chromosome all by itself is usually represented as a single straight or squiggly line and when you see this it counts as 1 chromosome. When the "X" is present, each of the two "single stranded" copies present on the "X' is called a "chromatid". Two chromatids are called sister chromatids if the two chromatids being compared are connected together on the *same* "X".
When you inherit chromosomes you get half of your chromosomes from your mom and another "duplicate set" of chromosomes from your dad. For instance, from your mom you get chromosomes that you can label 1-22 with an extra sex chromosome, and from your dad you also get a set of chromosomes which you can label 1-22 with an extra sex chromosome. You will find that the chromosome labeled "16" for mom will match up in its color patterns and size with exactly one chromosome from the dad which you can also label "16" so that they match. These two matching chromosomes are called homologous chromosomes. They are the chromosomes that are most similar to one another when comparing the set of chromosomes inherited by your mom to the set inherited by your dad.
Hope this helped.