Failed to install firefox mobile os b2g in ubuntu13.04

[hema2]

Hi,
I am trying to install firefox mobile os b2g on ubuntu . I have downloaded and installed gaia. But when I am trying to run firefoxmobile b2g I am getting errors. Can anyone please help me in finding where I am going wrong. Below are the steps I am following:
1. Downloaded b2g-26.0a1.multi.linux-i686.tar.bz2 (http://ftp.mozilla.org/pub/mozilla.org/b2g/nightly/latest-mozilla-central/b2g-26.0a1.multi.linux-i686.tar.bz2) from http://ftp.mozilla.org/pub/mozilla.org/b2g/nightly/latest-mozilla-central/
2. Extracted it in Downloads folder only.
3. From terminal I have downloaded and installed gaia using the command
git clone http://github.com/mozilla-b2g/gaia
then make -C gaia profile
4. When the profile is ready I tried to run firefox mobile b2g
testlab2@testlab2-HP-Compaq-Elite-8300-SFF:~/Downloads/b2g$ cd b2g
bash: cd: b2g: Not a directory
I tried this one also
testlab2@testlab2-HP-Compaq-Elite-8300-SFF:~/Downloads/b2g$ -profile /home/testlab2/Downloads/b2g/gaia
-profile: command not found

By the by here are my Ubuntu specifications:
Distributor ID: Ubuntu
Description: Ubuntu 13.04
Release: 13.04
Codename: raring
kernel version: 3.8.0-29-generic
kernel information: Linux testlab2-HP-Compaq-Elite-8300-SFF 3.8.0-29-generic #42-Ubuntu SMP Tue Aug 13 19:40:39 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
Can anyone please help me out to solve this problem.
Thanks in advance