As long as all of the equipment has the correct settings (including any security if you are talking about wireless) then you should have no problem. You can connect as many devices as you want.
For example i have 2 laptops, a PS3 and Xbox 360 that all connect to my router just fine.
Actually, most routers, reportedly, can support up to 255 devices; however, bandwidth is shared between all connected devices.
To connect another device, wirelessly, you'll need to know the router's SSID (network name), the encryption type being used by the router (WPA/WPA2 or WEP), and the network key (sometimes known as passphrase).
Once you get all this info, turn on (if not already) the wireless device you wish to connect. The device should automatically search for a wireless network within range. You may or may not find more than one network. If you do find more than one network, scroll through the list until you find your network (remember, SSID). Typically, the networks with the greatest signal are closer to your wireless device, so, if there are networks with the same SSID (I.E. Home, D-Link, etc.), try using the one with greater signal.
After you've found the correct network to connect to, you may be asked to enter a network key. If you are, enter the network key exactly, as they are case sensitive.