activate apache mods

[Noah]

okay how do I enable apachemods?  specifically the userdir mod


root at sffun:/etc/apache2/mods-available# ls
actions.conf          cache.load         ext_filter.load    proxy.load
actions.load          cern_meta.load     file_cache.load    proxy_ajp.load
alias.conf            cgi.load           filter.load 
proxy_balancer.load
alias.load            cgid.conf          headers.load 
proxy_connect.load
asis.load             cgid.load          ident.load         proxy_ftp.load
auth_basic.load       charset_lite.load  imagemap.load      proxy_http.load
auth_digest.load      dav.load           include.load       rewrite.load
authn_alias.load      dav_fs.conf        info.conf          setenvif.conf
authn_anon.load       dav_fs.load        info.load          setenvif.load
authn_dbd.load        dav_lock.load      ldap.load          speling.load
authn_dbm.load        dav_svn.conf       log_forensic.load  ssl.conf
authn_default.load    dav_svn.load       mem_cache.conf     ssl.load
authn_file.load       dbd.load           mem_cache.load     status.conf
authnz_ldap.load      deflate.conf       mime.conf          status.load
authz_dbm.load        deflate.load       mime.load          substitute.load
authz_default.load    dir.conf           mime_magic.conf    suexec.load
authz_groupfile.load  dir.load           mime_magic.load    unique_id.load
authz_host.load       disk_cache.conf    negotiation.conf   userdir.conf
authz_owner.load      disk_cache.load    negotiation.load   userdir.load
authz_user.load       dump_io.load       php5.conf          usertrack.load
autoindex.conf        env.load           php5.load          version.load
autoindex.load        expires.load       proxy.conf         vhost_alias.load
root at sffun:/etc/apache2/mods-available# uname -a
Linux sffun 2.6.24-23-xen #1 SMP Mon Jan 26 03:09:12 UTC 2009 x86_64 
GNU/Linux