how to jail break iphone 4 locked to soft bank japan to work on any gsm (worldwide) for ios 4,5,6?

i am about to buy iphone 4 white 16gb soft bank locked which is used but there are no scratches or cracks but without accesories and box for 200$ (including shipping) is it worth buying and can you suggest me other offers and also how to jail break it for world wide gsm. I live in india and my budget is low so please dont sugget me to buy factory unlocked one.i dont know what ios version is it so i want jailbreak for all ios 4 , ios 5 , ios 6 . Any help would be appreciated.Thank you and sorry for inconvinience, if any.

You know you used to be able to click on the edge of your title to change it? I cant any more.What happened?Is anyone else having this problem?