Question about UDAs - 

My workflow takes a couple attachments and pushes them to a field, then the workflow delimits these, send the delimited lists to a collection then iterates through that collection (adds some HTML) and updates that corrected list of attachments to a field in a Nintex list. 

The action works really well, but it's a little space intensive. I'd like to make it a UDA but i can't find instructions on what the inputs and outputs in this process should be?

I've attached what my current configs are, please how can i make that a UDA? 

Thank you