Um, search ? There's a thread stickied near the top of Q&A titled 'Flash Stock firmware/ROM + Root...' that has a simple root method, there's also a bunch of guides stickied near the top of the General section. I mean, this phone was released almost 3 yrs ago, 'how do I root ?' has been asked answered thousands of times already, and that's why we have stickied threads (so we don't have to regurgitate the same stuff over & over for n00bs who won't search).
And if your next reply is 'but it doesn't mention anything about 'l9100TDVLS3 build num: JZO54k,l9100TDVLSM Model num: GT-l9100T', you obviously don't understand what you're about to do & I suggest you read the guides/tutorials I mentioned above before you do anything lest you break your phone.