What specifically don't you understand about setting up the new tanks? It's straight forward with the manual they provide (see below) and youtube has a ton of videos on RS tanks all depending on what you're looking for. This community is also great if you have specifics on really anything we just need to know what you're looking for. Filtration and plumbing can be a huge topic so knowing specifics would help. Out of the box, you'll get everything you need for setting up the tank the one piece of equipment that you'll need to start out will be a return pump to move water back to the display.
For the 100g tank size in RS you'll want to take a look at the Reefer XL 525 (108g) or Peninsula 500 (105g) Keep in mind that this does not include the sump water volume. Waterbox would be my other recommendation for a tank they are the closest direct competitor to RS you'll want to look at the 130.4 (96.3g)
Let me know what specific questions you have I'm happy to help :)
Here are some links for you to start out your research:
Vivid does a series on RS 170 but the concepts are similar when it comes to the larger tank setup
Red Sea Tanks:
https://www.redseafish.com/aquarium-systems/reefer/#DELUXE
RS posts all of their manuals online here:
https://www.redseafish.com/wp-content/uploads/2014/11/REEFER-Series-manuals-all-models-1.pdf
Waterbox Aquariums:
https://waterboxaquariums.com/products/reef?variant=31632436428909
Also try the supreme guide:
https://www.reef2reef.com/ams/the-supreme-guide-to-setting-up-a-saltwater-reef-aquarium.84/