An Employer Identification Number (EIN) is a taxpayer number issued by the Internal Revenue Service (IRS). It is similar to a Social Security number for an individual but is used for a business. Every business must have an EIN.
You should create the corporation (file the Articles of Incorporation with the Secretary of State) and then obtain the EIN from the IRS. The corporation must have an EIN before it can apply for tax exemption with the IRS.