To access newsgroups just click on the top bar of the screen while Netscape is running and select "Windows" and then "Netscape News." You should now have a new window in front of the Netscape window. Just move it to one side so that you can look at both windows at once. (you may also have to chose the "Options" bar on the top line to pick "Show All Newsgroups.") Once you have a column of words in the left hand column, just click on the triangle next to the one that you want to start looking through. When you click on an actual newsgroup you want to read, the right hand column will fill up with the amount of messages curently being held and when you click on one of these the bottom half of the window will contain the full message to read.
Spamming is when you write something to the newsgroup that is not in relation to the topic set by the group. For example, you don't send a message about how you found a dog in your suburb to alt.tv.startrek.creative. more often than not it is used in refrence to people sending "Make $10, OOO in just one week" ads or pay for access sites.
Trolling is when you send in a blatant lie to a newsgroup in order to get a response. A good example of this is the recent thread of conversation (thread for short) in alt.folklore.urban claiming that Jamie Lee-Curtis is a hemaphrodite. This has been debunked many times but some of the people who first read it still believe it. Just like any medium you should never believe everything you see.