Serpentine belt

Yup. First look for the routing diagram on a sticker under the hood. If it is missing, draw a diagram so you can run the new belt the right way around the pulleys. There is going to be a spring-loaded tensioner pulley that will need to be released. If you tug hard on the belt, (do that with the engine not running!), You will see the tensioner pulley move. That one will have a hex head bolt in the center or a square recessed hole. Use a wrench or ratchet, as appropriate, to pull that pulley until the belt is loose and can be removed. Special wrenches are made for this job because it takes quite a bit of leverage to move those pulleys. I use a combination wrench with the box end on the bolt head, then a second box wrench hooked to the tooth of the first wrench to make it twice as long. Takes much less effort that way.

Be sure the belt is centered on each pulley that has grooves on it. Serpentine belts must never have any kind of belt dressing on them. If that was used on the old belt, scrub all the pulleys with soap and water before installing the new belt.

You should be able to handle it. Do you have a belt routing diagram? You use the proper socket with long handle ratchet or break-over. I hope the picture is accurate? You see the pulley with bolt in the middle, you put the socket there and pull, loosens tension on belt, then take belt off accessory. That tensioner spring may be stout, a long handle will probably help. If your going to work on your own vehicles, you need a tool set, sockets and wrenches, standard and metric sizes. I do not know the bolt size on the tensioner. The tensioner should be close to crankshaft.

The tensioner pulley isn't your best bet for the last one because the belt goes around close to 180 degrees of it. You'd have to pull both sides of the belt up 1/8th inch to reach 1/8th inch higher. That means stretching the belt 1/4 inch. Look for a non-ribbed pulley where the belt doesn't contact so much of it. There's usually another idler pulley where to raise the belt 1/8th inch you will only be stretching it a tiny fraction of that amount.

Also, every time I've run into this problem, I've found I didn't have the belt centered on one of the ribbed pulleys. A longer belt isn't the answer. An extra half inch can make some tensioner pulleys become almost fully-released and at the end of their travel.

I agree with caradiodoc. Did you get the proper belt?