Completely Lost on Adding Second Blog

So, I have been running WordPress for a domain (www.tanktronic.com) hosted at Network Solutions.

I want to make a second blog, completely separate from the first, with a different domain (not a subdirectory of tanktronic.com).

I installed a second WordPress installation in my hosting package, but that seems to be not working – I get internal server errors.

Any help pointing me to how I SHOULD be going about this would be greatly appreciated…