Here, read these if you're trying to Port Forward, which is required to host a server.
Mac
http://forum.blockland.us/index.php?topic=65941.0
PC {Follow the Links contained within this one}
http://forum.blockland.us/index.php?topic=40783.0
If you still can't understand it or it just doesn't work, then it's best to ask your parents or another responsible adult whom you can trust.
If you're still completely stuck or it still wont work, it's best to leave it be.
There's plenty of fun to have on other peoples servers. If you've got a friend who plays Blockland and you wish to play with them, it's easy enough to use an Instans Messenger with them to organise which servers to go on.