Now you have connected Kopete and your account. The window should look like this:
To add a contact press Add in the toolbar and choose your account (in this case it is your UIN), or you can use the menu → → . There you can enter the UIN of the person you want to add.
If you do not know the UIN, but perhaps the nickname or the e-mail address of a person, it is also possible to search for your contact. Click on the Search button.