Some random questions

The particle と (to) means "with" in this instance.

いっしょに (isshoni) means "together", I've never actually seen いっしょ (issho) separated from に (ni) like that.

Thus, 友だちといっしょに (tomodachi to isshoni) means "together with a friend".

[EDIT:] Just remember that particles often have more than one function. と (to) can mean "and", "with" and a number of other things depending on how it's used.

ah ok thank you! basically the problem was that the text book hadn't told me that "to" could mean sth different than "and" as well...."together and friend" sounded confusing to me^^