Okay, this is probably not something you want to try yourself. See if you can find someone in your area who does garage door repair and will do it at an affordable price. Or, if the springs themselves are broken but still attached to the wall, you might be able to use them until they break completely and then buy new ones.
If you decide to go the DIY route with this one, make sure you know what you're doing or your attempt can end in disaster.