how to add reference or import third party dlls (vendor's dlls) in netbean

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I've integrated Body Composition analyzer machine for health checkup purpose in .net website and it works fine on my local machine (cpu) but after hosting my website project to the server machine's iis whenever i try for a test through live url, The Bca machine is not detecting because it's connected to client machine's usb port.
I know the problem why it's happening.....


Now i'm trying applet code inside aspx page to open client pc port from live url and i open my client machine COM1 port successfully by clicking openport button of applet.
But when i click on webpage's test button, my bca machine is not entering in control mode and not read/write data.

Now i'm looking for add reference or import vender's dlls in netbean so that i modify the jar file and use dll methods to communicate device. but do not know how and where to add or import third party dlls. I googling for hours and tried but not found clear solution. Plz guide me step by step how to import dll.