The prosody of Latin poetry is explained in most grammars (including those free grammars listed on the Grammar Resources page). The brief summary filed at the bottom of the page, is usually enough for undergraduate students, but for a more complete discussion see the relevant chapters in the big grammars.
Allen, Joseph Henry, Greenough, J. B. and Kittredge, George Lyman. 1889. Allen and Greenough's Latin grammar for schools and colleges: founded on comparative grammar. Boston: Ginn and Co.
Gildersleeve, Basil L., and Lodge, Gonzalez. 1894. Latin grammar. Bost: Heath.
Bennett, Charles E. 1908. A Latin grammar. Boston: Allyn and Bacon.
and even
Kennedy, Benjamin Hall, and Mountford, J. F. 1962. The revised Latin primer. Harlow, England: Longman.
For a quick guide to the basic metrical patterns found in Latin poetry feel free to use the Wikipedia page.
For a discussion of prosody in general and its function in poetry refer to
Wilkinson, L. P. 1963. Golden Latin artistry. Cambridge University Press. pp. 89-134.
Links
Hexameter.co Test yourself!
Hexametrica is a tutorial designed to provide a basic understanding of the most common poetic meter, the dactylic hexameter.