How to get T-Mobile for jailbreaked iPhone?

[QueefSalad]

Ok, the title should be self explanatory. So, I recently jailbreaked my cousins iPhone 3.1.2 which he found and I unlocked, using blackra1n, and downloading cydia. So where do I go from there, to get this phone to be a working T-Mobile iPhone? I tried putting in my mom's t-mobile sim card, but it doesn't work, any help would be appreciated.

[battlecrushr]

install the source
blacksn0w.com
and then install blacksn0w

[QueefSalad]

do I install blacksn0w from cydia?

uhm blacksn0w is blackrain and i already have it installed since i used that to unlock my iphone and get cydia and ********** and stuff like that,

but now what i need help with, is how can i get the iphone to become t-mobile? i tried my moms sim card, but doesnt work, without the sim card it reads "No SIM" please help

[battlecrushr]

Do u hae a 2g or 3g

[QueefSalad]

3G

[battlecrushr]

Then it should work
make sure ur pitting sim in rite and that there isn't a turbo or universal sim
but u can go to settings
general
reset
reset network settings