Hi @nadine.benharrath ,
Since you're looking to create an API that would accept data for storing in a blob, I would create the API as a function app. For sample code, have a look at https://github.com/Azure-Samples/function-image-upload-resize. Even though this repo is over uploading an image and resizing it, the principals of storing data in blob are still the same. For more examples in other languages, check out the various code samples.