Stamp 4 through marriage.over 1 year no visa

Hi just want to ask if an irish national got divorce,and marry a non eu, who has no visa over a year,once they are married,what is the procedure to apply stamp 4?but was legal in the country for 7 years.

Please can somebody help?i just want to know of i have been in the country 7 years legal and 1 year illegal,after marrying irish can i directly apply to the immigration office or i have to go through solicitor.