To drain the brake fluid you will need to remove the cap and lock nut from the brake fluid bleeder valve on the caliper. It is a small valve with a lock nut on it and a Rubber cap to keep the dirt out of it. If you attach a small clear hose to the valve and loosen the lock nut you will be able to squeeze the brake lever or pedal (as the case may be) and begin pumping out the fluid. It works best if you can have two people doing this (although you can do it by yourself), one to squeeze the lever and simultaneously pour the new fluid into the resevoir and one to hold the drain tube into your oil pan and ensure it stays on the bleeder valve. I recommend using a clear tube so that you can see when the old oil is out and the new oil begins to come through and flush the system. Once the new oil begins to come through your drain hose close the locknut on the bleeder valve and top off your resevoir. When flushing the line you want to pour the new fluid in the resevoir simultaneously to avoid sucking air into your brake line. If the resevoir runs out of fluid you will get air in the line which causes a weak and wallowy feel in the brakes. Another option is to buy a hydraulic brake line bleeder, Motion Pro makes one that is relatively cheap as well as numerous other companies. These just make the job slightly easier and prevent against getting air in the line. As far as the type of brake fluid to use, check the brake fluid reservoir cap on the handle bar and the one next to your rear brake pedal. On the cap it will tell you Use only DOT 3 or DOT 4 brake fluid depending on what the manufacturer recommends. But DOT 4 is the typical recommended fluid for most bikes.
To drain the coolant you will need to remove the drain plug located on the waterpump cover. On some 250's there is also a second drain plug on the side of the cylinder to more easily drain the fluid that is run in the jacket surrounding the cyllinder. This may require you to remove the exhaust pipe in order to get at it. If it does, just remove the exhuast springs at the cylinder port and unbolt the pipe from the frame and you can pull it off. When you go to reinstall the pipe following re-installation of the cylinder drain plug ensure you loosen the silencer mounting bolts to ensure you get a proper fit and seal between the pipe and silencer joint before bolting it all down. Once it is drained you will be able to refill the radiator from the radiator cap on top by simply putting in the recommended amount of coolant/water. You will want to use a 50/50 mix of coolant and distilled water. Distilled water as opposed to tap water because tap water can be "hard water" containing minerals and iron which will cause pitting and deposits in your radiator.
If you have an owners manual or service manual get it out, and it will explain exactly how to do both of this projects. If you dont have one, get one, they are an invaluable tool. I hope this helps.