How more direct do you need than a message on your user talk page? You get a visible alert at the top of every wiki page you look at until you read the message after all.
(Then again, I just realized that I wasn't alerted to your replies above until I found them in the recent changes page... I wonder if something's broken. I'll talk to the other admins about it.)
Simply now, what is it that you don't understand? There are explicit instructions on the upload page, including the instruction to pick a license in Bold Text. Have you simply been skipping over that block of hints and instructions on the grounds that there couldn't possibly be anything important in it? In that case, let me try to explain in more detail.
When you upload an image, right under the mass of boilerplate buttons there are two controls which you seem to have been ignoring:
One is the Licensing dropdown. It's marked with the word "Licensing". As we've said many times, including right there on the upload page, you must always pick a license when you upload an image. Sometimes the web page or site where you got the image makes its license terms clear -- and you select the item on the dropdown that corresponds to their license. If you know for a fact that it is too old to be under copyright, you choose "public domain". If you created it yourself you pick "I created this image myself". If you got the image from Wikipedia, you choose that option. And if you have no idea, or nothing else seems to fit -- pick "Fair use", the very first entry.
The other control looks like this:
Click the plus sign, and type a category into the edit box that appears. It's got a progressive search built in, and will offer you categories that match what you have started to type, If you're uploading an image for use on a work page, put the name of the page here. If it's going on a trope page, put the trope name here. This too is stated right there on the upload page, where we would think you might have noticed it.
Outside of those two controls, the Summary for an uploaded image, should always always always include the source of the image. In almost all cases this should be (at the absolute minimum) two URLs -- one to the page where you found it, and one with the URL of the image itself, with enough text to identify which is which. Give the website's name. Give some idea of the ownership of the original image and its copyrights. Use my changes to your last couple uploads as a model.
If these instructions make unwarranted assumptions about how much you know about how to edit pages and/or find your way around the wiki, let me know and i will point you at pages here that provide more basic instructions on how to contribute meaningfully.
-- Looney Toons, admin
CC: @Labster, @GethN7, @Robkelk, @QuestionableSanity, @DocColress, @LulzKiller, @SelfCloak