use the following search parameters to narrow your results:

reddit:'{name}'

find things posted in {name} only

author:'{username}'

return things submitted by {username} only

site:'{domain}'

get links to pages on {domain} only

url:'{text}'

search for {text} in url

selftext:'{text}'

search for {text} in self post contents

is_self:{1|0}

include (1) or exclude (0) self posts

over18:{1|0}

include (1) or exclude (0) results tagged NSFW

e.g.(and 'dog' reddit:'aww' site:'imgur.com')

see the search faq for details.