People who frequent USENET tend to fall into one of two camps: those who like to download headers and bodies for all articles, and those who like to download just the headers and then pick and choose which bodies they want. At the moment, Pineapple News is better optimized for the first case, but both are possible. You can probably guess which camp I fall into.
To get full articles for a newsgroup, make sure its download mode is set to “Full Articles.” To change a group’s setting, control-click on the icon for the newsgroup in question in the storage view, and select “Newsgroup Prefs.” Then you can double-click on the newsgroup to initiate a download, or else select the Transfer menu, then Download, then Group. You don’t have to do anything else but wait for the articles to arrive and then read them.
Make sure the newsgroup in question is set for Download Headers by control-clicking on its icon, selecting “Newsgroup Prefs,” and then changing the setting for “Download Type” to “Headers Only.” Double-click on the newsgroup to initiate a download, which will start the headers streaming in.
Based on a message header’s subject, author, and so on, you can decide whether to download it or not. The most direct route is to double-click on the header, which will add an action to the request list to get this article’s body. Alternately, you can control-click on the header to get the context menu and select “Mark for download.” The header’s icon should change to include a red arrow.
Once you’ve marked a bunch of messages for download, you can retrieve them by selecting the Transfer menu, then “Download Marked.” That will get you a sub-menu with several options, which allow you to get marked messages for the current thread, get all marked messages in the current newsgroup, and so on.
By default, the program limits the number of headers and articles downloaded to 300 of either, then it goes on to the next action. You can change this setting globally, per-account, or per-group. See the help topic Newsgroup Preferences.
When you first subscribe to a newsgroup, sometimes you don’t want to spend forever downloading or reading possibly thousands of messages that are already in the group, you just want to see whatever is posted from now on. That’s what the Catch-up function is for. It updates the saved state data for a newsgroup to make it look like you’ve already downloaded every article that currently exists in the group. Then you can come back to the group the next day, download it normally, and you'll see only what’s been posted in the last 24 hours. On the Transfer menu, you can find a sub-menu called Catch-up that has options to catch up the current newsgroup, all newsgroups for the current account, or all accounts. You can also find this command on the context menu for newsgroups.