Yikes, RH 7.2 is seriously old. Anyway, just grab the ypbind (and if you need to serve, the ypserv) RPMs from a Red hat mirror, install them with rpm -ivh, and configure /etc/yp.conf and any other config files you need to set. Then you can turn them on in with "service ypbind start" (same for ypserv if you need it) and make sure they're on in chkconfig.
Don't install ypserv unless you need it (i.e. the machine is to be an NIS server).