Hello, welcome to the forum! I do not agree with you buying a rescue as a first horse, but since you have already bought him, I'm going to try and give you as many resources as possible. Please keep in mind that although these things are helpful, you still need an experienced person with you atleast the first time or two. I also would like you to answer the questions already asked about the horse. Can we get any backround on him? Whether or not he has ground manners, is saddle trained, etc, makes a HUGE difference.
Here are some basic videos, links, etc on things you'll need to know about horses. How to Put a Halter on a Horse - wikiHow
-- this link is good, with nice descriptions and more links on how to make sure your halter is on the right notch, or how to use a halter made from rope instead of nylon/has a clip at the throat. It also has the parts of a halter listed, tips, and warnings signs to look out for.
this is a good herd-scenario video on horse to catch your horse. I personally would rather loop my leadrope around the horse's neck, then halter him, however.
this is a video teaching you how to tie up a horse. this is EXREMELY IMPORTANT,
especially with a large horse like yours who you know little to nothing about. this video is ONLY for if you have a metal fence to tie your horse to. If you have wood for a fence, use the pole that is driven directly into the ground, not the horizontal pieces that are only nailed on.
If your horse were to get scared and pull on the rope (which is very possible) the rail would break and could hit him or someone else.I advise in only watching this video up to 2:30.
this video is a how-to on cleaning a horse's hooves. This will be very important with your gelding, because of the shape his feet are in. Horse Behaviour
this site is an all-together great first time owners guide, as it has links to basic horse health, care, behavior, etc.
There are many other things, but I need to go ^^ I do want to say this, though.
Horse ownership is a HUGE thing financially, timewise, and healthwise. If you are not willing to enlist a trainer for yourself and your horse (I'm assuming that you know little about riding) pay vet bills (your horse WILL get hurt at some point, especially in a herd of 15 horses in a large pasture) and are not able/willing to go out to the barn atleast 3 times a week, pay for yearly shots and checkups, exercise your horse, bond with him, sacrifice for him, etc- I really think that you are better off trying to sell him to an experienced person who is willing to work with him. Its great that you rescued him, and I'm sure you mean well, but rescue horse and an inexperienced person in a situation like this spells out disaster.
Saturday may be too late for his hooves if he is developing sore in his feet. Try to atleast call the barn and ask them if there is anything that can be done.
I wish you luck and safety. Feel free to message me with ANY questions.