You might want to check the
tutorials to get a better hang of the commands you need to use.
In the case of repair: you have to equip the item you wish to repair in your left hand and then use the /repair command. The repair process will start then and depending on your skill the system will tell you how long it will take.
EDIT:Thread moved. Thanks Neko... or was it Mord? Well, to whom it may concern then.