Can someone point me in the direction of a detailed tutorial? I can't get my minimap working on my new map :(

http://developer.valvesoftware.com/wiki/Overview

I made a minimap following the directions posted in the link but when viewing my minimap in either mini and full screen mode it looks really awful, like a poorly compressed jpg with lots of artifacts. I used the same format as my custom textures and those look fine. Any ideas?

Check how Source takes your screenshots. Be sure they are TGA/PNG format rather than JPEG.

Don't forget to add the .txt. .vmt and .vtf files into your BSP using Pakrat.

I made a minimap following the directions posted in the link but when viewing my minimap in either mini and full screen mode it looks really awful, like a poorly compressed jpg with lots of artifacts. I used the same format as my custom textures and those look fine. Any ideas?

sounds like possibly you didn't change to a high res setting before taking the overview screenshot?

I used 1280x1024, it was saved in TGA format using the screencapture command which i bound to 'p'. after I edited the picture down to 1024x1024 I saved as uncompressed 24bit TGA.