We use the particle に for saying that something is present at a certain location.
Note how あります is translated with to have in the sentence above. To have is a second meaning of the verb ある.
When an event or action is happening at a particular place, we use the particle で instead of に.
Note the お in front of 店. The お is an honorific prefix, showing respect to the person or object you are talking about. There are several words that commonly go together with this prefix. For example, it can also come in front of 水 to make お水. Using お is polite, and in casual speech you would just say 水 and 店.
Finally, the particle で can also be used to talk about the means/mode by which something is done.