sesearch -A will show you every thing that is allowed, and gives you (a lot of) lines like:
allow httpd_t httpd_t:dir { getattr ioctl lock open read search };
Which says that things (i.e. processes) with the httpd_t label are allowed to perform getattr, ioctl, lock, open, read, and search operations on directories with the httpd_t label.
ps -Z and ls -Z will then list the labels of processes, and the labels of files and directories. If your processes label does not have an allow rule for your file label for the correct action you are denied.
The only trick really is that when it reports a label as say "system_u:system_r:httpd_t:s0" thats 4 different colon separated fields and the only one you really care about is the type field "httpd_t", because thats what the rules are defined for (unless you're the NSA or doing Very Interesting things (the other fields are user, role, and security level, but the default Red Hat etc selinux policies dont use them))
There is no wiki with definitive list of labels because they are just strings and the policy writer can call them what they like, even the _t suffix is just a convention to denote the type.