Highlandman

You might try starting with the Wikipedia article (I am not being facetious) and following the video links there. Especially the section on "Types".

http://en.wikipedia.org/wiki/Sea_shanty#Types

"Haul Away Joe" is a so-called short drag chanty. One pull at the very end, on last word.

Long drag chanties, which is fairly synonymous with halyards chanties generally have (or can have) 2 pulls per each refrain. The pulls are almost always evenly spaced and occurring on the downbeats of measures. The intent is that they should be obvious--they were designed that way. If you give a specific example of one that might be a little confusing, I or someone can answer.
Gibb