how can i go to italian street from tianjin railway station?

It is very near, about 1.2 miles. You are suggested to take a taxi to reach the street at a cost of CNY10 around.

thanks sarah and where are you suggest me to visit it in the city?

which one is better between the attractions? Ferrise wheel, Eye of TJ, Haihe Cultural Square, Haihe Cultural Square,etc?

Well, all the scenic spots you mentioned win high popularity among tourists. It's worthwhile to visit those places.
In addition, you can also go to Ancient Cultural Street. You can buy various folk crafts, and sample the delicious local snacks there.
Have a good trip!