One of my radiator hoses blew of how do I replace it

First drain the coolant into a bucket - there should be a drain on the bottom of the radiator. There will be a hose clamp on each end of the hose. You will need a screw driver or a good pair of pliers depending on what type of clamp you have. Loosen the clamps up, remove the old hose and clamp the new hose on. I would replace both the upper and lower hoses while you are at it. Refill the radiator with new coolant when you are done.

Don't forget to bleed the air out of the system, aka "burp" the radiator. Since you'll be replacing lost coolant anyhow, this is also a good time to replace the thermostat, and check the thermostat housing for hairline cracks.

An engine/radiator flush would also me recommended.