Remote Desktop options already set allow to connect and password is set.
But whenever you reboot and try to connect, you only see black screen.
Well you need to install tigervnc-server. I am using Fedora then
$ sudo yum install tigervnc-server
Edit /etc/sysconfig/vncservers to your desire, but keep in mind that:
1. Make sure the setting of `1` then  should match.
2. Check using ps -ef | grep vnc, and find rfbport 590X.
where X shud match your configuration
3. If you set to config 1:yourusername then the rfbport will be
5900 + 1 => rfbport 5901, where 5900 is the standard port of vnc
4. Similar to #3 if you set config 2:othername then the rfbport will be
5900 + 2 => rfbport 5902
5. When you try to connect do not forget to specify to which port you
are trying to connect. IP:PortNumber, 192.168.0.1:5901.
If no port specified then default port to be connected is 5900
6. Check your firewall, make sure it allows connection to tcp with
destination port 5900:5910 (port 5900 to port 5910)
7. auto start vncserver during startup, in my fedora simply
$ sudo chkconfig vncserver on
Hopefully you will have successful connection to your target remote desktop
without any login at the target remote desktop.