Yes, thank you - that seems to be the problem

i don't understand.
I have an iPhone 3G, 3.1.2(7D11), modem firmware 05.11.07.
Can I jailbreak?
I downloaded Pwnage Tool, it asks for ipsw - I download and try load 3.1.2 7D11
"wrong firmware bundle selected"
The above instructions seem to require a rudimentary understanding of ipsw's that I don't possess,
help?