Hi, I have access to most of the books I need in order to get the spells I want because these books have been shared with me. Two examples of this is the players handbook and Tasha's cauldron of everything, this was so i could get access to both Hex and Mind Sliver, one of which is a first level spell and one is a cantrip. Why do they not show up on the list over spells i can choose for my Human Warlock? 

I also have access to some of the books irl, but i want an online character sheet, but cant choose some of the spells because i didnt buy the books  from here? im so confused

For books that have been shared with you: sharing works by campaign. Someone turns on sharing for campaign A, and you have a character in it, that character can use the books owned by anyone else who has a character in that campaign. You can read the books through the megamenu, but use in the character builder is limited to characters in that campaign. Is the warlock in that specific campaign?

As for books you have in real life, you can use the homebrew tools to input them here, if you don't want to pay for them again (either in whole or in part, for things like spells and subclasses, you can usually buy them piecemeal from the marketplace, and that will go towards the cost of the full book if you buy it later).