Jailbreak and unlock Iphone 3g 3.1.2 baseband 5.11 using Cydia and Blacksnow

Unlock and Jailbreak Iphone 3g Firmware 3.1.2 and baseband 5.11

Install (jailbreak) Cydia on your iphone using Redsnow 0.92
Then to install Blacksnow, use Cydia as follows:

step 1: go to cydia and add a source blackra1n.com
step 2: go into source or search for blacksnow
step 3: click on blacksnow and install it

Voila