First you need to install XChat on your machine.
If you use windows you have to download it first from http://silverex.org/download/ and install it. (Just double click on the downloaded file and then use the wizard).
On Linux there are different ways for every distribution.
Commands you have to type are shown italic. The '~$' only indicate that your are on commandline as normal user, '~#' indicates that you are root.
On Debian:
Go to the command line (open Terminal, XTerm, Konsole)
Become root:
~$ su
You will be prompted for the password (you do not see what you are typing):
~$ Password:
~# apt-get install xchat
If you are asked if you wish to continue press y (it could be another letter, depending on your language)
Of course you also could use a Graphical fronted like Adept, Synaptic, aptitude or things like that to install the package 'xchat'.
On Ubuntu
~$ sudo apt-get install xchat
You get asked for YOUR password, please type it (you won't see what you type) and press Enter.
If you are asked if you wish to continue press y (it could be another letter, depending on your language)
Of course you also could use a Graphical fronted like Adept, Synaptic, aptitude or things like that to install the package xchat.
After installing XChat, just start it (it should be somewhere in your menu (differs from Linux (KDE, Gnome, XFCE, ...) Windows).
At first startup the Network list looks similar to the screenshot (although maybe in a different design or language).

At "Nickname" just enter your Nick.
The next two fields are there for alternative nicknames, in case the one you provided first is already in use. At field number four you enter what your ident should be, if you do not know what this is, just set it to your nickname.
At the last field you could enter your real name, but keeping in mind your privacy, just put in your first name or nickname.

Now we have to add the ScoutLink Servers.
To do that click on "Add". In the new window click on "newserver/6667" and then on "Edit". Now enter the Server name as shown in the screenshot "chat.scoutlink.net/6667". Then press enter.
Now set the info according to the Screenshot. Don't worry that the Screenshot was made with the german version, the position of the items should be the same as in every other language.
If you have problems with 'umlauts' you maybe want to change the character set to ISO-8859-15. But normally the System default is ok.
There are some more things you can change here but they are not necessary for a first start and so they are not described here.
After you have done the changes click on "Close", then choose "ScoutLink" from the Network list and then click on "Connect" at the bottom right.
And now? More information what do to after you have installed your IRC-Client is available at our "First steps" page.