MS SQL Query Indexing

I have 3 tables

City ( CityId , Name )

Items( Itemsid , ItemsName , HotelId , CityId)

Hotels (HotelId ,HotelName)

Im trying to write a query to get Hotelname ,City Name,  Number of items in that hotel in that city in that database

Query :

select count(i.Itemid), h.HotelName, c.Name from Items i inner join Hotels h on i.HotelId = h.HotelId inner join City c on c.CityId = i.CityId
group by h.HotelName, c.Name

How can I index the joining fields ?

This is a continuation for question

https://www.experts-exchange.com/questions/25101051/MS-SQL-Query-Help.html