How can I start learning Arabic

You can start with Medina Arabic Language course found online. Its free and very effective for a basic knowledge. It's also named Duroosul Lughatil arabiyyah.

Some Resources:
 
1. Download Madina book (1st part), key, handouts from here: http://www.lqtoronto.com/downloads.html

Madina Books - Arabic Text, Madina Books - Key (English), Madina Books - Handouts, Blank Verb Conjugation Sheet.
 
2. And start from 1st post of this page:https://www.facebook.com/pages/%E0%A6%95%E0%A7%81%E0%A6%B0%E0%A6%86%E0%A6%A8%E0%A7%80%E0%A7%9F-%E0%A6%86%E0%A6%B0%E0%A6%AC%E0%A7%80-%E0%A6%B6%E0%A6%BF%E0%A6%95%E0%A7%8D%E0%A6%B7%E0%A6%BE/331484620390003?fref=nf

3. আরবী vocabulary শেখার জন্য দারুণ একটি android apps www.appsapk.com/learn-arabic/