I have yet to figure out how to edit the menues and add launchers to the taskbar.
For the launcher, right-click on the panel, choose "Add New Item", pick "Laucher", add more items to it if you need, choose an image for the launcher (either the one on the list, or choose other to browse for an icon -- you'll find several icons in /usr/share/pixmaps), type in the command for the program you want to run.
The basic menu structure is in Setting --> Menu Editor. The application menus, however, are dealt with by reading .desktop files that are in /usr/share/applications . If you open one of these desktop files (right-click on it and open with a text editor), you'll be able to change the Category where it goes and the command that they run. To add a new menu entry, you'll need to create a new .desktop file and put it there; to remove it, delete the corresponding .desktop file or place it somewhere else. Granted, it's not as easy as in KDE, and takes a while to get used to. I have a sample desktop file that I use whenever I want to add a new program to the menu. Change accordingly. Categories can be Office, Network, etc. (Multimedia is AudioVideo, though... I know, it's weird). Place the icon are in /usr/share/pixmaps.