I have a phone 3gs activated and jailbreaked but not unlocked on 3.1.2 and want to save my shsh using tinyumbrella on 3.1.2. Can someone instruct me step by step how to do this?
You can not save SHSH for 3.1.2 now. That should have been done long time ago before 3.1.3. And now since 4.0 and 4.0.1 is already out you can not even save SHSH on 3.1.3 or 4.0. Only option is to save on 4.0.1.
Cydia server is not going to generate any SHSH and it is the Apple update server, which has stopped on 3.1.2, 3.1.3, 4.0 after releasing 4.0.1. So there is no hope...