couldn't exec de_dust.cfg means you don't have a de_dust.cfg
no challenge/bad challenge is a result of the way querries are handled by srcds/hlds since they changed it. you can get rid of it by using sv_enableoldquerries 1 or just ignore it
the other one looks like it's looking for a sprite that you don't have.
a quick search of these forums should've returned a few server configs. you can also go to http://www.cstrike-planet.com/cfgmaker?cfg=srcds and it'll generate a server.cfg with your settings, then you copy and paste it into a text editor and nameit server.cfg