In its most basic form:
create a .desktop file (paste the text below in an empty file):
[Desktop Entry]
Name=Start Teamspeak
Exec=/bin/bash /home/flux/Downloads/TeamSpeak3-Client-linux_amd64/ts3client_runscript.sh
Icon=/path/to/your/icon
Type=Application
save the file as team.desktop in ~/.local/share/applications and drag it from there on to the launcher.
Explanation
Running scripts from a .desktop file
If you run a script in the Exec= line from a launcher like this, it works like in the terminal:
If the script is not executable:
language /path/to/script.language_extension
If the script is executable, just:
/path/to/script.sh
If the script is executable, the language extension is not strictly needed. However, if you use it on the file, also use it in the command.
Running more complicated shell commands from a .desktop file
Exec=/bin/bash -c "your_complicated_command_here"
(command inside quotes)