can i able to install MAC OS X by my external hard drive?

hi there i got Macbook now my CD drive does not working however i got my external hard drive to connect into my macbook, so i have copied teh .dmg file into my external hard drive now i don't know what settings i have to do to get it install though.

i coul dnot get into my macbook cause its says "you need to restart your computer. hold down the power button for several seconds".

so somebody please help me to do by my external hard drive

thank you

What .dmg file are you referring to and where is it coming from ?

Cheers ... McBie

i mean i have copied CD from to my external hard drive which is snow-leopard 10.4.32.dmg file now i am stuck and don't know what is the instructions though

You are very confused. All version of OS X.4 are Tiger, not Leopard and sure not Snow Leopard. If you have an OS on your machine, simply connect the external and copy the OS and all files using SuperDuper.