Type of keyboard,
version of game (PC/Ps2/Xbox?),
any other information?
If you are trying to switch to a compact keyboard setting (WASD configuration) then you need to open your menu and go to config, and one of the options that I can not remember offhand holds the keybinding and switching options. You can opt for the presets or choose your own keys for movement, healing, etc.
I don't understand what the main problem is here, though. I understand you want to find a way to bind keys to movement, but you could be talking about a wide array of situations. If it is in fact due to a compact keyboard and you are having a hard time finding a way to open the menu, hold the (fn) key and then use your "-" for what would be the numpad to open the menu in game.
If it's just simply a movement issue and you have figured out how to open the configuration menu then you just need to look into the options and find the correct submenu.
I want to convey most is to be able to want width of the choice of the weapon to spread to be able to enjoy a player.