To add Avast! to the Mint Menu:
1. Right click on the Mint menu and choose edit menu. This will open a window with three "columns": "Menus", "Items" and some buttons.
2. In the "Menus" column choose the subheading you want Avast! under and click it so that it it highlighted. (You specified Administration, it's the one at the bottom).
3. In the "buttons" column press the "New Item" button. This will spawn a new window named "Launcher properties".
4. In the Launcher Properties window set the fields as follows:
Name: Avast! Antivirus
Comment: (Anything you like, not necessary)
5. To set the logo click the little "spring" image at the left of the "Launcher Properties" window and enter the following into the address bar of the icon browser:
6. Close the icon browser, launcher properties and mint menu windows.
7. Right click the mint menu and choose "Reload Plugins"To add Avast to the quicklaunch toolbar(I'm assuming you mean the area to the right of the mint menu icon as it would be in Windows.)
1. Right click on any free space on the bottom panel/taskbar and choose "Add to panel".
2.Select "Application Launcher..." and hit the "Forward" button
3. Click the small triangle next to the Mintmenu subheading (Administration) that you placed Avast! under to open the list of applications in that subheading.
4. Select Avast from the list and hit the "Add" button. The Avast icon will appear on the panel/taskbar.
5. Right click the avast icon and hit "move". Drag the avast icon to where you want it and click to place.
Apologies to those who would like a terminal command answer.