Anyone know of any websites that show you how to install these shingles. Going to put them on our new shed. Thanks!!

We have a 3ft. by 11ft. chimney with a brick exterior. When we get heavy rain some water runs down the chimney block below the roof damaging parts of the ceiling and sheetrock walls. It also is coming through the masonry around the lintels of two of the three fireplaces. When we go into the attic we can see that all the block on the one 11ft. side that we have access to is very wet. On the 3ft. side that we can see, the two courses of block nearest the roof, towards the peak, are also wet. The chimney’s brick exterior has some small holes in the mortar joints about 3/8 in. square. Some of these have been sealed with some kind of silicon caulk or adhesive. A couple of the mortar lines near the top of the chimney have been sealed/repaired with NP1. There is some moss growing in a number of the mortar joints, especially on the north side. The crown looks good with some minor repairs with NP1. The previous owner replaced the roof in 2004, just before we purchased it. The top of the counter flashing is embedded into mortar joints. It does not look like it is new but it is not corroded and is tight against the brick with no apparent holes or gaps. Contractor number one said the problem is that the chimney is acting as a large sponge and once it’s full of water it is released and we get the water problems. His solution is to install flue caps, apply Drylock paint to the crown, clean and repair all the mortar, and seal the brick. Contractor number two says the chimney flashing needs to be replaced and the mortar repointed. If contractor one is correct we can do the job ourselves. If number two is correct we’ll look for a roofer with sheet metal expertise. How should we proceed?