Well, here's a list of working directories that you can submit to for getting backlinks:

SUBMIT RSS FEED: 71 Aggregators & Directories List

As to how you can submit them, it's pretty straight forward. Just enter your RSS feed, title of the RSS feed, and category you want the feed to be placed in and hit the submit button.

Normally these sites have instructions on how to do it as well though, so if it differs you can read what they say. But it's pretty much the same for most sites.

Here is a big list of RSS directories you can submit your RSS feed to - RSS Submissions