I installed mplayer, a font, all of the codecs, and a skin but when I try to open mplayer it gives this response:

MPlayer 1.0pre6-3.3.4 (C) 2000-2004 MPlayer Team
CPU: Advanced Micro Devices Athlon 4 /Athlon MP/XP Palomino (Family: 6, Stepping: 2)
Detected cache-line size is 64 bytes
CPUflags: MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 1 SSE2: 0
Compiled for x86 CPU with extensions: MMX MMX2 3DNow 3DNowEx SSE


vo: X11 running at 800x600 with depth 16 and 16 bpp (":0.0" => local display)
Failed to open /dev/rtc: Permission denied (it should be readable by the user.)
Setting up LIRC support...
mplayer: could not connect to socket
mplayer: Permission denied
Failed to open LIRC support.
You will not be able to use your remote control.

and nothing happens.

Could someone please tell me what I have to do to get the gui working.

Thanks

try it as root

when I type the command gmplayer as root it says:

command not found

To install gmplayer, you need to compile the source package with
./configure --enable-gui
make
make install

Furthermore, you need to have GTK development packages installed for the GUI. If you're using the command line version (mplayer), you need to tell it which file to play. So, "mplayer" alone will achieve nothing, try "mplayer /home/me/myvideo.mpg" or whereever they are. Use "mplayer --help" for a list of command line options. Use "man mplayer" to read the whole manual.
The line with /dev/rtc might indicate that your hardware clock is out of sync. Reboot your machine, go to BIOS setup (should tell you which key to press, most likely "del"), there you should have the clock settings somewhere.


HTH