Hello I am here in the US on a work visa and my spouse is on dependent status.
She's not entitled to get a SSN.
How do I get a ITIN number for her? And
I got married in 2009, Can I claim her on my taxes i.e. Is there a particular amount of time that I need to be married to claim her on my taxes?

Spouse is never you dependent. However, you can file joint return as residents with your spouse. Attach W-7 (ITIN application) with your tax return.