I would like to know how to put syslinux on my sd card and I have tried using extlinux. However, I keep getting the message
Missing Operating System. Please help me.
The error message
Missing operating system indicates the BIOS has looked at every device in its list of allowed boot targets, and has not found anything that looks like a legitimate bootloader.
This can mean one of three things: either the installation of the bootloader on the SD card has failed; or the installation was successful but the system BIOS is unable to read a bootloader from a SD card; or the BIOS is not configured to attempt booting from a SD card, even if it could do so.
Not all SD card readers provide boot support: some require a driver to be usable, which restricts them to be useful only after an operating system has been loaded.
If a card reader appears in the OS as a generic USB storage device and is usable without installing any special drivers, the system BIOS might be able to access the reader+SD card combination as a generic USB disk. In this case, you should try setting the BIOS boot settings to "boot from USB".