Can you please let me know how to get to Jiaozuo from Weinan or from Xian, preferably by train?

From Xian railway station, there are three ordinary trains running at 09:37, 14:17, and 17:32 respectively. The train takes about 7.5 hours to reach. Ticket price for soft sleeper is CNY205, for hard sleeper is CNY133.
From Weinan railway station, there are two trains. They run at 14:59 and 18:12. The duration time is 7 hours. Ticket price for soft sleeper is 186, for hard sleeper is CNY123.

Thank you June!
Ideally, I would like to stay there fro a few days. Do you know if there are any hotels/hostels? I had a look on internet but it looks like all hotels are located away from the city.

Thanks dear.

Yes, there are many economical hotels near the city center.
What's your budget about your accomodation?
You can go to Victoria Hotel. The price is CNY 200 to 300 per night. And it provides warm services and comfortable living environment. You can go and see. It's located at 100m east of intersection of Jiefang Middle Road and Jiaodong Road (Huajing International Plaza).
Hope you like!