Counter-Strike: Source Console Commands
Open console by pressing key `/~ at your keyboard which located to the left of key "1". If no console appears, check your keyboard shortcut in the game, maybe it was changed or try type "-console" as a game parameters in "set laucnh options " for steam.
To connect an IP or custom server, just type "connect" command. Sometimes, hosted game not appeared in server list so you have to do this which usually occur for LAN game.
The "sv_* " command are command for server settings when you host/create a game. Notice that when you type sv_ , other command will show with its initial value. Scroll with arrow keys. Just type any command without any value to show its function. Always remember the initial value in case you wants to play with normal settings.
For example, by changing gravity using command "sv_gravity", it will change the game gravity. Sometimes, playing with non-standard value makes the game more fun.
The "mp_* " command are commands for map/game settings. It only affect only when you host or create game.
For example, "mp_startmoney 1000" gives you $1000 when the game started. There are many commands there which you can change.
Some command need to restart the game for the changes to apply.