In this case, "someone" opens (something on the web) with a new tab, we say: (Someone)が新しいタブで(someting)をひらく。 If "something" opens by itself, though it's impossible, you can say: (Something)が新しいタブであく。 It's the difference between transitive verb and intransitive verb. In Japanese, in many cases, we have different forms/verbs, however, there are exceptions. If you need examples, I'd like you to let me know. One small thing: 読み方はどうやって？--> どのように読みますか。 I hope this helps you.

ひらく、です!