how to place an order for a new iphone and pick up at apple store -Dubai

You need to start with the online Apple store that serves Dubai, not the US version, and set up the pickup that way. You cannot order from the US online store as Apple are constrained to follow US Export of Technology regulations.

As your fellow end users, we have no way of knowing if Apple extends the "pick up in store" option to all geographic areas. Talk to the Dubai store staff or contact Apple's corporate presence there:

Hi fifi166,

If you'd like to purchase an iPhone, the following article shows how to do so and your different options: iPhone - Shopping Help - Apple

Essentially, you'd just order it and select the option to pick it up from store, if available.

Cheers.