No, just type them in.
This releases and renews your ip address should something go wrong with your internet connection, maybe your modem dropped your ip, etc
regedit opens up the registry, but only use this if you know what you are doing as it can render your os useless should you delete the wrong key, always make a backup before you change or delete anything in here.
ping command will tell you if you are reaching anyone out on the net say like yahoo. type ping www.yahoo.com
and if you are online, you will get a reply back, if not, you will get a request timed out.
sfc /scannow cans your pc for protected files that may have been changed and if it finds one or some, you will be prompted to insert your os cd to replace those files with the originals.
The netstat command is used to display the TCP/IP network protocol statistics and information.
Check here for some more: