Install:
a, Do this if you only want to install YSM3 as your secondary firmware:
- Copy the TTMenu folder the SRESET.DAT and the YSM3.nds to the root of your sd card.
- You can boot YSM3 from the YSM3.nds in your main firmware.
b, Do this if you want to use YSM3 as your primary firmware:
- Copy the files and folders which is in the A point plus the SYSTEM folder too.
- In this way YSM3 will autoboot. 

Note: 	You don't need to copy the tools folder into your sd card.
	You can use cheats by putting usrcheat.dat into the TTMenu folder.
	http://cheats.gbatemp.net/

Updating YSM3:
No matter if you installed the A or B version you only need to copy the TTMenu folder into your sd card.

If you're installing this as a secondary firmware make sure you have the latest version of M3 Sakura from handheldsources.net