How to implement it on steam community ?

Hie there, I want to create a bot like this.

which communicate with steam in order to send trade offers , accept trade offers and payment to users as they will sell CS:GO skins to us.

I have created a similar project but as website not on steam community as show in screen-shot for selling CS:GO skins.

Please can any one tell that how could I achieve this on steamcommunity.com ???

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