clean install, new hard drive

Hey guys

I have a macbook, the first generation of the allumijum ones (late 2008 i think) and recently it had a fall. As a result the hard drive is dead. So, i bought a new one. A samsung ssd. Before changing my hard drive when i was trying to boot it was giving me the folder with the question mark and when i was trying to boot pressing the alt key it was giving me only the mouse pointer. I also have a bootable usb with osx lion but when i boot with alt it gives the option to choose it but the then it gives me the forbidden sign. I haveno other hard drive on it qhen i am doing this. If i plug the ssd it doesnt see the usb.is there anything that i could do?

Thank you in advance.

Thanks for the advice. How do you explain the fact that when both ssd and usb are pkugged in the usb is not recognised?

Yes, when i dont press alt it gives me a folder with a question mark.

my ssd is completely empty (just took it out of the box and plugged it in) and my usb has capacity of 8gb. do i need to do anything else to my ssd before plug it in? i dot want to transfer any data to it. i just want to install the os on it.