Make sure you have a DHCP server on the network. Go to the admin panel of the router, navigate to network settings and check the box next to "Automatically assign IP addresses to network devices". Possible other names of this item, more precise information can be found in the help system. Optionally, you can specify ranges of issued addresses, and lease time - the period for which the client is issued an IP address. If the connection to the Internet is through network without a router, check how to configure DHCP with your ISP.
Make sure that the DHCP client running on the computer. To do this go to control panel, start menu "Administration". Select "Services". In the list look for the DHCP client. Configure the service to start automatically and then start it manually. This may require administrator rights. After the computer restarts, verify that the service is still running.
To enable DHCP on network adapter, go to network connections. In this folder you can have multiple network connections icons. Select, right click, drop down menu, click "Properties". Choose in the list the TCP/IP Protocol. Click "Properties" select "Obtain an IP address automatically" and "Obtain DNS address automatically". Click "Apply" and "OK". If the server is configured correctly, after a few seconds the computer will get an IP address. You can verify this on the "Status" tab of the network connection.