Create a recipe that notifies a channel

I am new to and I am trying to learn how to create integrations via recipes. For learning purposes, I am trying to create a recipe that notifies a slack channel on a built in trigger.
My first obstacle is that, I dont know how to automatically include the userid in a payload that is sent to my remote url that I setup in my custom field. I asked the question here .

My second obstacle is that, when I get a payload to my run-url setup in the custom action, I do not receive sufficient information in the payload. I get a payload like this for a recipe whose built-in trigger is for ‘item created’

{"payload"=>{"blockKind"=>"action", "blockMetadata"=>nil, "inboundFieldValues"=>{"space"=>{"title"=>"general", "value"=>"xxxxxxx", "invalid"=>false}}, 
"inputFields"=>{"space"=>{"title"=>"general", "value"=>"xxxxx", "invalid"=>false}}, 
"recipeId"=>123, "forceNoCharge"=>false, "integrationId"=>123}, 
"monday_webhook"=>{"payload"=>{"blockKind"=>"action", "blockMetadata"=>nil, 
"inboundFieldValues"=>{"space"=>{"title"=>"general", "value"=>"xxxxxx", "invalid"=>false}}, 
"inputFields"=>{"space"=>{"title"=>"general", "value"=>"xxxxxxx", "invalid"=>false}}, "recipeId"=>123, "forceNoCharge"=>false, "integrationId"=>123}}}

In this payload, I have no idea which user created the item, the item name and the board name. My question is how do I get these details to be added to the payload?

I have created a screencast to explain what I am trying to do. I will be glad if someone can help me out as I am stuck on this.