Creating a Variable Code to get the following URL

Hi There,
Im need to create the following url from a form on my website this button needs to get to the following url after they fill in the form. the under lined parts are what need to be variable from what they enter in the form, the Bold needs to generate in order. This code needs to be in the 'Submit' Button that transfers them to this external site.
https://www.payway.com.au/SignUpClientNumber=Q16750&PlanName=Starter695+P6&Addressrequired=true&FirstPaymentDate&CustomerNumber=1588&CustomerName=bluepoppy+studios&returnURL= 

Confusing I know.
Clare
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