The easy option is to take the tires your local tire shop. But that cost extra money and time. Done right you can install the tires quickly, safely and easily. Done wrong it can take hours, end in failure and frustration or injury.
If your old tires have been on for a couple of decades you may be better off taking to a tire shop. You may end up fighting for hours trying to get the old tires off.
Put your new tires in the sun for as many hours as you can afford. We usually allow them to sit in the sun for several days. Before putting them in the sun place two or three strips of wood or some items 6" to 8" long in the tire to stretch the tire open. This will make sealing the tire with air much easier once you mount it on the rim. The tires come somewhat narrow in the rim area and can take hours of stress, struggle and strain to get a seal if they are not heated and stretched open.
If it is winter you will need some method of getting the tires hot or at least warm. If you cannot get them hot it could take hours of struggle ending in failure.
Be sure to use lubricate when installing the tire on the rim. Tire tools can be purchased at Harbor Freight.
Once the tire is on the rim if you cannot get the bead to seal wrap a ratchet strap around the tire and tighten forcing the tire lip closer to the rim bead sealing area and apply air. CAUTION: DO NOT APPLY MUCH AIR. AS SOON AS THE TIRE STARTS TO SEAL RELEASE THE LOCK ON THE RATCHET STRAP. BE CAREFUL. IF YOU HAVE ALREADY INSTALLED TO MUCH AIR WHEN YOU RELEASE THE RATCHET STRAP YOU COULD BE INJURED. REMEMBER AS SOON AS AIR IS BEING RETAINED INSIDE OF THE TIRE IT IS APPLYING PRESSURE TO THE RATCHET STRAP MECHANISM AND WHEN IT IS RELEASES, IT WILL RELEASE WITH AN EQUAL AMOUNT OF FORCE TO THE AIR PRESSURE OF THE TIRE. BE CAREFUL WE DO NOT RECOMMEND YOU DOING THIS UNLESS YOU HAVE EXPERIENCE AND ARE WILLING TO TAKE THE RISKS.
Heat is the key to not needing a ratchet strap.
Once the tire is holding air the next challenge is to get the tire bead to seal against the rim. Do not over fill the tire in order to get the bead to seal. Each tire will have a MAXIMUM air pressure that can use used to get a seal printed on the tire. DO NOT EXCEED THIS LIMIT for any reason. Add lubricate to help the tire seal if necessary. CAUTION: KEEP YOUR FINGERS OUT OF THE BEAD SEALING AREA. WHEN THE TIRE SEALS IF YOUR FINGER GETS CAUGHT BETWEEN THE RIM AND TIRE YOU COULD RECEIVE A SEVER INJURY AND IF YOU TRY TO JERK YOUR FINGER OUT IT COULD CAUSE EVEN MORE INJURY.