How you would fix the rubber hose connecting to your dishwasher depends on which hose it is. For the most part the hoses that connect your dishwasher can be easily replaced by disconnecting the old one and connecting a new one. Hose replacement is normally covered in your users manual for your dishwasher. If you don't have a manual go to the manufacturers website and the information you need should be there.
Is this the hose supplying water to the washer or the hoses that go to the air gap next to your faucet (or straight to the drain)? Both should ideally be replaced. The supply should definitely be replaces regardless. The hoses that go to the air gap come in two sizes (5/8" and 7/8") and an air gap equipped washer will use both of them. Any hardware store will have inexpensive replacements. You could patch a hole in these with heater hose repair tape (from the automotive store) or silicone 'Tommy Tape" from the electrical department. If there is no air gap make certain that the drain hose is replaced in exactly the same way under the sink as part of it needs to act as a sewer gas trap.