need professional video for my startup - that will be used in promotion.

hello how are you. i am working on a startup. its mainly social media manager like buffer.com
I need a professional promotional video creator who has experience on this and has worked on such projects.
you will be required to create a video which explains the featured my website offers. you will required to mainly work on script, voice over and explain video with proper graphics and pictures of features on how they work.
if you think you can do this then please send me some past examples of your work. thank you