sql server - TSQL Use ' in string assignment

Trying to use a single quote and assign it to a variable so I can create a dynamic report.

The problem is when I do this:

set @Statequery = (' and PostalState = ' ')  +  @PostalState  + '''

If you do this, print @Statequery, it needs it to look like this.

and postalState = 'QLD'

How do I escape the ' character in this case?

Thanks for your help in advanced,

Ryan