How to display a popup window on click of a link in form?

Add a quick task(with help instructions) in the process which runs in parallel to the active task and make use of this quick task as a link to show as a popup in another SAIL form.

bharathwajanr587  The feature you are talking about is called modal window in some technologies and it's not viable in Appian by any means for the moment(at least till 17.1).

In case if you are using SAIL and the architecture is DB record centric I would suggest refraining from doing any fancy things such as quick tasks as they will introduce a deviation in the already established architecture. Also, quick task keeps the process active which is not really recommended just for sake of instructions and more over it just takes you to another task rather than coming in a pop-up.

I would suggest educating the end users about what's doable and what's not in Appian.

There is no popup/modal dialog feature in Appian currently. What you could do is to add a link to a web page that is opened in a new tab/window.

Another option is to use a dynamic link to show/hide a help section in the form. The content can be loaded dynamically.

Why popup?

If it is instructions it can be a part of interface, there are few options:
* make it a separate interface rule and show before input interface
* use instructions and tooltip fields in the interface to describe user what is needed
* have it as interface part able to show / hide on a button click