The host name of your computer is just the name of your computer. You can call it anything you want, but it is best to give it a single word short name like the name of the room it is (DenPC, KitchenPC, MikeLaptop, etc...)
the NETWORK host name is the name used on your network and is usually just the name of your computer also (see above). Sometimes this is also a name set in your network router if you use one to connect to the internet. You can usually set this to anything also.
There should not be really anything you can set either of these two that will cause too much of a problem.
If you are looking to use your computer to go to Craigslist and apply for jobs, then the first thing you will need is an Internet connection. Generally, this takes you going to an internet provider and getting a cable, DSL, or dialup internet connection. They should give you everything you need to connect your computer up to the internet. When they do their part, you should be able to open Internet Explorer and type CRAIGSLIST.COM into the address bar, and the page will come up. If it does not, you need to contact your Internet Provider and tell them you need help setting up their connection. You pay them for it and they need to assist you.
After you have an internet connection and you can get to Craigslist, you should be able to answer job postings. When you do, the poster will receive an email and then respond back to you. To receive their email, you need an email address.
the best way to get an email address (and free) is to go to one of the sites below and make an account. They will give you a free email account and email address that you choose.
You would sign up for a free account, select an address, and then start replying to ads.
Be very aware that a lot of ads on Craigslist are not real and they just want you to send them your information. Be very careful.
If you need anything else, just let us know, but try to be as descriptive as possible and tell us what you are trying to do, what you expect to happen, and what is happening.