how to Geoprocessing specific area in the layer

[abdullahqasrawi]

I have a model which used to find the best location for gas station, I would like to make this model work in a specific area selected by user which mean I want the model to be working in area of interest as i define in the attached screenshot.

Any help please?

[DanPatterson_Retired]

If a selection is made in any layer prior to any geoprocessing step, the selection is used.  You would need to set either your analysis extent in the Environments tab, or perform a selection prior to running that step.  In any event, you might want to produce and use an AOI (area of interest) featureclass to limit your processing to its extent one way or another