Api connector modify a value dynamically

Hello, I am French, excuse me for the translation.

I use an api “geonames.org

in the get url, I want to be able to dynamically modify an argument

http://api.geonames.org/findNearbyPostalCodesJSON?lat=50.433&lng=2.828&radius=10&maxRows=0&username=test

I want to change the argument radius=10

according to the value of an input on my page.

I understood that I could put in brackets the value to modify and add a key to it

radius=[dynamic_radius]

and give it a value: example 5

and everything works

I would like to put the value of an input but I don’t know how to do it

I tested this which of course doesn’t work I don’t know how to format the argument well

could you help me on this subject please

uncheck private, and in front end use any input value you want, by get data from external Api function, there you can add dynamic_value dynamically

Thank you very much, your solution solved my problem