@farish

u will be having installer application if your phone is unlocked.

if u are using firmware 1.1.1 then i would refer you to use wifi to connect to internet
and then goto installer let it refresh the source and go to install tab you will lots of softwares.

find sources tab and click on install
this will add new sources and u will be able to download more content

but if u are using 1.0.2 firmware
then u can use ibrickr also
but still i would refer you to install application through installer only by using wifi connection. and if u dont have wifi then use brickr and connect phone to pc through data cable and enjoy the features of ibrickr.

ibrickr wont work with 1.1.1 firmware but u can give a try

@ aditya

to unlock iphone visit this link

this is the best link u will find to understand how to unlock

other sites are