You dont actually have to do anything. You just tune into the frequency and it should tell the tower that you have for example information Alpha. Initial contact I beleive means when you first call a frequency as you said
“#1Advise on initial contact means just that you will provide the ATIS code when calling in for the first time.
#2 When with approach just switch frequency without asking to ATIS you should be able to pick it up around 60NM from the airfield. Wait for it to start playing then, switch back to approach it will play the entire ATIS even if you switch prior to it finishing.”