When XChat is first started it brings up a window with 5 main parts:
On startup 1 window is created with no state (it is labeled "<none>"), if you join a channel that window then contains all the information from that channel. If someone /msg's you a new window may be created containing all further /msg's from that person
The menu bar has 6 menus in it (the text may change if you have language packs active):
The tool-bar contains the leafs of each window attached to the main window, these leafs have the name of the channel or nick of the window. Clicking on one of these leafs brings that window to the front. If the text in a currently hidden window changes the text in the leaf goes red
The "X" button at the far left closes the currently window. If that is the only window XChat quits. The text box contains the topic of the channel which is currently active in the top window or the address of the nick, if a nick is currently active.
The "^" button (or an up arrow if you use GNOME), next to the "X" button, links or delinks the window. If you have a series of tabs then clicking this will delink the window and make it a separate window. After this, clicking it again will link the window back into the notebook. You cannot delink the only window in a notebook and if you try to link a window when there is no notebook window then one will be created.
The buttons at the right of the tool-bar set the channel modes, and only have effect when the window contains a channel and you are chanop. They stand for:
The far right button, with the arrow, toggles the user-list
The text box contains the text from the contained object (channel, nick etc) and the output from commands entered into the input box.
It is usually a GTK text box, whose options can be controlled from "Settings - Setup - Channel Windows". However it can also be a ZVT (Gnome only), and this allows extra options like pseudo-transparent backgrounds.
The user-list contains every nick in the current channel. Nicks may have a green or yellow dot to the left of the nick. A green dot marks a chanop and a yellow dot shows the nick has a voice (e.g. can post to a moderated channel)
Below the list are a set of buttons, which are controlled from "Settings - User-list Buttons". Clicking on one runs a certain command with reference to the selected nick in the user-list.
Right clicking on a nick brings up a pop-up menu which can be configured from "Settings - User-list Pop-up. Selecting one runs a certain command with reference to the clicked nick in the user-list.
Multiple nicks can be selected by holding down the Shift key.
To the left of the input box there is a label, containing your currently active nick, possibly with a yellow or green dot to the left of it see 3.4.
Entering text into the text box and pressing enter will process the entered text. It can be processed in 1 of 2 ways, it is either sent to the contained object (a channel or nick) or if it starts with a "/" it is processed as a command.
To the right of the input box is the conference toggle. When set this squashes all join/leave messages so you can have an uninterrupted conversation.