Hello @Arshad Nazeer ,
connecting an IoT device to the cloud to see telemetry and also control it from the cloud is a common scenario.
There are a number of scenarios available you could consider, these depend on a few things: what are the capabilities of your device (is it internet-connected, what telemetry does it share), do you want to build it on PaaS resources or do you want to make use of SaaS, etc.
The most common pattern is connecting your device to an IoT Hub so it has a secure (two-way) cloud connection. From there, telemetry is moving through the cloud either as events or persisted. Within this process, the telemetry is usually aggregated, filtered, enriched with other data or alerts are derived.
Regarding your ASP.Net website, polling for data updates is not that efficient. Websockets (eg. Azure SignalR services) are a welcome and efficient addition for live updates of your webpages all over the world.
The IoT Hub also supports the ability to send commands back to devices. The Azure IoT Hub SDK helps you to program against that interface and control your devices.
MS Learn has a lot of tutorials and hands-on labs about IoT. Take a look at this extensive collection.
A single post will never cover the complete 'world of IoT'. Please think big but start small and try out what works for you. Just reach out if you have more specific questions.