Depends on what is wrong. First step is to disassemble the cylinder..if the leak is small (seepage) then you can typically rebuild it with kits availible online for less than 100 bucks and a few hours. If a kit you order does not come with instructions, you can usually find disassembly/install instructions on the web. Unless the shaft is bent or excessively pitted, this is the cheapest and easiest way to repair it.
If it is the hydraulic cylinder itself you will have to replace it. If it the boom arm a capable welder should be able to repair it.
That depends on where it's leaking out; if it's at the master cylinder, you have a bad master cylinder, if it's at the wheel cylinder you have a bad wheel cylinder if it's at a caliper... well, you get the idea. If you know how to repair a master cylinder, wheel cylinder or caliper, you can often get by with a little savings but it's usually best to just trot down to your local auto parts retailer and get a new or rebuilt one.
no! if your seeing white smoke its a leaking cylinder head gasket. which is a major repair. see a certified auto tech to perform this repair.
If your bathtub pipe is leaking, it requires immediate repair.
If your home radiator is leaking, it needs immediate repair.
If your toilet bowl is leaking, it requires immediate repair.
Is your garbage disposal leaking and in need of urgent repair?
If your shower pipe is leaking, it may need immediate repair.
Is your window leaking and in need of fixing?
The kitchen sink pipes are leaking and require immediate repair.
If your bathroom sink pipe is leaking, it requires immediate repair.
First you have to identify the fluid that is leaking then locate the source of the leak before we can tell you how to repair it.