How is a scientific name written?

I am going to assume that this question refers to the final part of the scientific name. That would be the genus and species name. The rules regarding how to write these names are very specific.
Fortunately, they are also very simple: The genus name always precedes the species name. The first letter of the genus name is always capitalized. The first letter of the species name is never capitalized. The entire name is always underlined or italicized.
For example, the gray wolf's genus and species name would be written as follows: Canis lupus. It is possible to abbreviate the scientific name. In order to do this, the first letter of the genus name is used and the species name is used in full. The italics or underline rule is still present. Canis lupus = C. lupus.
http://generalhorticulture.tamu.edu/h202/labs/lab3/sciname.html