So this is the way I used to use the website. Click on Active Topics, filter the forums as show below, and access most topics in the first page by tapping on either "View xx new", "Last Page", or just the last number in the "Page" counter.
Alternatively, the "New/Updated Topics" page will display only the topic with new content (the "update" red tag appears when an author edits a topic, which also makes the "Last update" date change, tagging the author of the last reply occasionally).
I sometimes filter the topic to make my visit quicker, but then "Reset" it later to eventually take a glance at other games' posts updates.
If the first page of a topic in open, the "Last post" button opens the last reply-post, either if it is in the current page or not.
The "Bookmark" button in the topic's text (Reply #1) will check the topic towards your Topic bookmark feed, while the same button in any reply below will send such reply to your Replies bookmark page.
...and this is how your Bookmark section looks like.
I check Topics which I may want to revisit later, or even see how many views it is getting with time, and Replies that are particularly helpful and will serve as reference in the future.
The "My Followed Topics" page displays topics which you created or replied to (I guess), and is quite usefull when you don't have much time and just want to check the topics which you are already interacting in.
Most reference pages are shown until here. Each link highlighted in the right-hand side of the pages, as well as the links for the tags (displayed under each page's title), can be right-clicked and saved to the browser's bookmarks, or sent to a spot or folder on the Desktop/Home Screen.
... and this is how bookmarks look like.
Note - Bookmarks saved to the browser's list do carry the forum filter eventually applied, while bookmarks sent to the home screen apparently don't, prevailing the filter/reset option that was active in your last section.
Replying to a post - note that the "Post reply" refers to posting a reply to the..Post itself (the current topic), while the "Reply" button found at the end of each numbered post is better suited to responding to that specific message, attaching p at the beggining of your answer a link to the text you are responding to.
The "Quote" button also helps identifying the responded post, even though it is sometimes desirable to trim the quoted text in order to highlight the specific fragment under consideration.
When mentioning a different reply (or a post from a different thread), the #xx tag can be right-clicked and have its link copied, while the "(Reply to #xx)" link displays the reply which was used as a source to the current one, and can be copied as well.
Hope this helps, and at the same it gathers more tips about the usage of this great website!