Please Evaluate My Covers

Hello everyone!
I am pretty new here, new to stamp collecting in general. Could someone please explain to me what I should be looking for in covers? What makes them valuable and what are the type to keep an eye out for. I am starting from scratch - only know what I can find online, and it seems websites are vague.
Anyways thank you in advance!

It is vague. Very vague.
What makes a piece of "postal history" desirable or interesting to one collector will be entirely different to another. Interest to a collector does not always equal monetary value. Some of my most treasured items have almost zero monetary value. What makes an item interesting? It could be the stamp, the cancel, the date, the rate, the routing, what happened along the way, the sender, the recipient, the message, etc., etc. Additionally in the Antiques Roadshow mantra, so much of an item's value is "condition, condition, condition". There is no easy or quick answer other than to collect what you like and don't get too caught up in the value of an item.

A few things that add value that come to mind are:

1) First or last day of use
2) Crash mail
3) Items with actual ties to historic events
4) Items addressed to or from famous persons
5) Great advertising art or subject matter
6) Former Countries

There are many more but as John said there is dollar value and "interest" value

I would peruse past and present auction catalogs on Stamp Auction Network (SAN) from houses such as Schuyler Rumsey and Cherrystone and others to get a feel for it.

https://stampauctionnetwork.com/auctions.cfm

Material of recent vintage (post WW II) may be of value if the message content is significant. As has been pointed out - maybe impt. people or impt. events. Or maybe just interesting - for example - a postcard home from young people to their parents after visiting a world fair might be interesting. Value is in the eye of the owner and in the eye of the potential buyer.