How to change mouse cursor and theme?

How can I change X11 cursor and theme in the newest Ubuntu? I can't find it. Please help.

In order to get your custom cursor to work with all applications do:

1. Download a cursor theme.

2. Open Gnome Tweak Tool and change the cursor theme.

3. Open a Terminal.

4. Run this command:

   sudo update-alternatives --config x-cursor-theme
   

5. Select the number corresponding to your choice

6. Log out.

7. Log back in.

It is quite easy to change the cursor in Unity.

1. Open a Terminal.

2. Type in these commands:

   sudo apt-get install gnome-tweak-tool
   sudo apt-get install oxygen-cursor-theme
   sudo apt-get install oxygen-cursor-theme-extra
   

3. Select a new cursor theme from the Tweak Tool.

4. Run this command:

   sudo update-alternatives --config x-cursor-theme
   

5. Press Alt+F2, type this then press Enter:

   compiz --replace
   

(Alternatively reboot if compiz --replace doesn't work)

Maybe its too late for reply, but i faced a problem using this in 12.04. If you download a Cursor theme and extract it to /usr/share/icons/, make sure change its permission to 755:

chmod -R 755 cursors/

and change the Cursor theme in /usr/share/icons/default/index.theme to your theme.

then apply instruction described by suli8