how do I get my rebate on my microwave that I just bought

As Andrew said.

You can usually submit them online. Sometimes they want a picture of your receipt too. It takes upwards to 90 days sometimes of these things.

I really dont know you have to call the customer service for exact answer but i believe you have to send a copy of your reciept and a rebate form which came with the item fill it out and send it to the given adress but please check with them first i do not work for them.