posting Job offers for the H1B

I have heard that it needs to be posted lets say in craigslist or in a newspaper the Job Title or the possition my sponsor company is doing for me so they know im verry qualify for the possition is that correct? When and where should I posted and for hoW long if i want to aply this April 2013 for the H1B ??

There is no minimum requirement.

What they want is that your employer should make genuine effort to find a suitable US candidate. This can be done by posting in US newspaper, or online job boards etc.