Since these functions aren't as essential to Counter-Strike's gameplay as the commands on top, you can place them anywhere you want. If your mouse doesn't have a wheel, you should bind the individual weapons to the number keys on your keyboard. In fact, since you can only carry one primary and one secondary weapon at once, you're better off doing the latter. Some newer mice, like Microsoft's Intellimouse, have upward of four buttons, which gives you more options when choosing where to bind your keys. Some players prefer to use the keyboard's arrow keys for movement, and you should take the time to find a control scheme that's the most comfortable and best fits your style while still letting you perform all the game's necessary tasks.
Proper control can mean the difference between life and death.
Once you've got your control set up the way you want to, you should go to the customize menu in Counter-Strike. Here, you can pick out your character's online name and spray paint image and color. This moves your character's arm and weapon from the left side of the screen to the right, which makes it easier to get accustomed to the screen's layout, especially if you're used to playing other first-person shooters, most of which draw the weapon on the right side of the screen anyway. One final suggestion is to jump into the game's video options menu and move the gamma slider as far right as possible. This will brighten the screen and make it easier for you to spot hidden enemies in corridors and low-contrast maps like Office and Cobble.