[SOLVED] HP Compaq NX7400

[agent_kith]

It doesn't let me do the installation, it gives me an error.
in none of the two files.

There are two kernels, install and upgrade.  In the WebApp, you can only perform a kernel upgrade.

With install kernels, you'll need to modify your boot USB. In the linked thread, there is a section that outlines how to modify the boot USB with a custom kernel. Follow the steps listed there and things should get going.