Hello Alex, welcome!

Good idea on a library and looking at Scott's catalogues (6 volumes), usually found in the reference section (at my library anyway) as the ones in the regular take out shelves are always gone.
Color pictures in the catalogues now a days too. Bonus.
These are general catalogues. That means only he most common stamps and their varieties re listed or shown. For some countries you may have varieties that are not shown. For these you need specialized catalogues that are available for each county.Don't despair, this should be pretty easy without getting too involved.
Or, if you don't want to go through all the trouble and time of
ebay (it can be sometimes) then there are large auction houses that specialize in selling collections. I am not familiar with them myself. One is Seigal (I think) , google it. Google 'stamp auction house'.
Trouble is the auction house wants money for their knowledge and time too. You will mostly not get the suggested retail price listed in cataloges anyway unless the stamp(s) are of a quality condition and rarity that demands it.
Even selling on
ebay works better when you know a bit about a stamps pricing factors (condition, condition, condition) or the proper name or abbreviation used for it or them. Search around on
ebay (click the worldwide button to get more info on worldwide stamps) and see what others sell stamps of a certain design type or era or issues. Like King George 6 is usually abbreviated like KGVI (Roman numerals) or GVI (in England mostly) or long hand George VI or 6. Depends on who is selling it and what your target market is.
US stamp[s usually sell better in the US, Canada stamps in Canada, etc, etc. So use the names the US sellers use or Canadian or whoever so they will find it when searching.
Even if you just sell pages, having the names of the monarchs like Queen Victoria, QV, King George 5, KGV, France's Napoleon, (did I spell that correctly?) USA's Washington or Franklin or similar helps a whole lot to help interested buyers of that material find your listing.
Certain people have
ebay email them whenever a listing is found that has their searched-for words in the title.
So, selling all at once to an auction house or a private collector (who is relatively reasonable in his pricing) (get a few people looking) and don't forget you can always ask here for opinions on what something could go for or what is possibly there that could be worth looking into further.
The same stamp, looks the same to a new fellow, or even some of us oldies that have not had experience in that country or area, could be worth 10 cents or $10 or $100 or $1000 to the right person.
But don't worry. If you do not have years to learn and study stamps, and all you want to do is get rid of them, you will be able to do that. it is just that knowing more lets you see what is there and what to pay attention to and what to ask a higher price for. Especially if it is presented well and correctly labeled and has good scans or pictures taken of it (them).
Time is money, the old saying, can be also used to mean the more time you spend the better chance you will have of getting the nest dollar.
I know a bit about this and that and have, while selling on
ebay over the last few years, learned more and more than I ever knew. Just because it helped me sell. And I know nothing compared to some collectors.
It's not rocket science (usually), it's not magic (well, some would argue . . .), it's just presentation.
Don't worry too much about describing how good it is. A good picture (do the back also) will show them that. They can see for themselves. On a black background so the perforations around the edges will stand out. Don't enhance the picture any more than sharpen it 25% or so at max. Don't adjust the colors.
People can see good stuff and good stuff sells. Bad stuff doesn't sell.
I mean all this as good advise, not meaning to tell you how to do anything. Just some experience I have had that you may find something interesting in. That's all.
Good luck.