No Modules Appearing, Etc.

I should start at the beginning and mention that when I installed PM and enabled it, I got the error "Could not create directory /var/www/[domain name of host]/[subdomain that I use]/http//sites/all/themes". I did not yet have the folder "themes" in "sites/all" (my installation uses the "sites/default" folder), but I have seen references to it before and figured that maybe I should just make it myself. So I did. I disabled and enabled PM, and got no error messages. Whether this means anything good, I don't know.

Next, I tried to search for modules to install (this is how you update existing modules, too?). The Modules page presents categories, but clicking any of them, "Import/Export" for example, brings me to the Site Building section of Administration, even though the address is "admin/build/plugin_manager/modules/Import_export". Does this mean PM never installed properly from the start?

Searching does not work at all. The first time I searched, I got these three messages in this order (this is from memory, not verbatim):
Repository is old or out of date.
Repository is old or out of date.
Repository has been updated.

I didn't know what else to do, so I hit Queue for Installation and one message went away (or, put another way, I got the other two messages again). I hit it again and the other one or two messages went away. But nothing else happened, which makes sense since I was probably supposed to be seeing modules that could be selected before hitting that button.

The server my friendly acquaintance is letting me use runs PHP 5, that's all I know about it.