I know that to play maps that I download, I have to click "import bonus maps" then click on the map-but it only shows me .bmz files. How do I play maps that I download that are .bsp?

u must put the bsp files in to C:\Programme\Steam\SteamApps\YOURS SETAM NAME\portal\portal\maps

and then you must type in console map "THE NAME_OF_THE_MAP"
and then the map load

badumpbumpbump wrote:
I know that to play maps that I download, I have to click "import bonus maps" then click on the map-but it only shows me .bmz files. How do I play maps that I download that are .bsp?

This is not always true. This is only for maps that come in .bmz

Did you read the readme with the map you downloaded?

about the map load, what would the thing you type in look like? show me exactly what it would look like in the console. lets say the map is called cool_bibble

You would type "map cool_bibble" (without the quotes).