Did Gunner's suggestions not work for ya?
The way I do it is to download the source - in the parent directory from where Cyril sent ya (those are all .rpm's which I've never had any luck with - feel free to use 'em if they work). I like the .tar.bz2 version, but .tar.gz and .zip all have the same contents (.tar.xz too? I think that's a new one). Put it in the directory you want to untar under.
"tar jxf nasm-2.10.6.tar.bz2"
"cd nasm-2.10.6"
become root, if you're not, or prepend with "sudo":
"./configure"
"make install_everything"
unbecome root.
Now you should be ready to assemble. If that doesn't work, let us know where it fails. "sudo apt-get install nasm" should be easier, if it's supported on your system. I'm not familiar with Linux Mint...
Best,
Frank