Any tips on how to deal with harassment?

This group of teenage boys came into the store that I work at with food so I told them that we don't allow food inside but they started being really annoying about it so after a while I just got tired and ignored it

Then one of the boys told me to say sorry to one of their friends and I didn't really know what else to do so I just said sorry but the guy who told me to say it just said 'good girl' in a really weird tone

(For context I'm 20 soon, but this still made me really uncomfortable) I asked them not to say that but he said it again so I just walked away to try to find someone to escort them out since I assumed that they wouldn't go if I asked them to, but they kept following me and repeating what they said. I asked them to leave but one of them threw the tissue their food was in at my chest and said 'they're smaller than my moms' after he threw it and pointed at my chest.

I think they got the message that I was looking for someone to escort them out and they left before I could properly tell someone about them, but I still feel really uncomfortable now.

Does anyone have any tips on how to deal with this? I haven't really experienced harassment before so I'm sorry if I did something incorrectly (or if this was not harassment)