why are you searching user names? if you see a post, click on the username and it will bring up info. you cannot get a persons real name etc. only see horses they own or other info they have added. You can search post by user names. etc.
If you enter the username of the person you're looking for into the search bar (you can find that by scrolling to the top of the page, in the navigation bar) you should be able to find all of the posts / threads they have been active in, or tagged in.
try sending them a private message. if you start tpying in their username, the system will recognize it, if the member is registered. but, you must have it exactly right, including cap/no cap or spaces or ?