Editing Exixting library components in altium

[Ankur]

Hi,
Like you, i have also moved to altium from eagle,
My doubt is that -
for example imported any library of an IC using import wizard, but after importing i had to make some changes in drawing of it's symbol as well as in footprint, how can i do that, when i am right clicking in library tab over that particular component then i see the edit option as grey, i.e. disabled.

Please tell me the steps to edit it.
Also find attached the screenshot.

thanks