You will need to file an I-130 Immediate Relative immigrant visa petition and have it approved by USCIS. Once approved, the immigrant visa will need to be processed through the National Visa Center and sent to the consulate for consular processing.
The previous answer is correct that this will take anywhere from 6-12 months.
Stanley Dale Radtke, Esq.,
220 Montgomery Street, Suite 416
San Francisco, CA 94104
Your spouse may enter the United States on a K-3 non-immigrant spousal visa, or an Immediate Relative immigrant visa. The K3 visa was originally invented to lessen the amount of time that spouses were seperated after they were married. You could file for an immigrant visa and while that process was pending you also filed for a K3. When your K3 visa was approved your spouse could come the United States and be with you as a "non-immigrant" until the immigrant visa (IR1/CR1) was approved. However, it is no longer necessarily true that the K-3 is a faster alternative. And note that as of February 1 2010, when both the I-129 (needed for a K-3) and I-130 petitions have been approved by USCIS and sent to the NVC, or when USCIS approves the I-130 before the I-129F, the availability of and need for a nonimmigrant K-3 visa ends.
In any case, your spouse should be able to come to the United States by the time your child finishes school next April if there are no other complications.
If you would like more information, feel free to contact me.