Incorporate table field into URL string

I'm sure i'm overlooking the obvious, but here's what i'm trying to do.

I have a field called Application Number

There is a URL whereby the construct is always the same with the exception of the record it's looking for.  So it would be like, "https://yada/bla?FirstTime=True&ApplicationNumber=[Application Number]" 

How do i call upon a field in the URL, and furthermore have the field also be the name the URL is using?  I tried referencing the field in the URL and the URL is deciphering it as literal text, not the field value.

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MICHAEL SARGENT
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