OP: "I'm aware that my monitor might not show everything in a correct way. You can tell me now about calibration but I don't have the money for that spider thing or whatever it is."
I understand that at the moment, you can't spend money on an external hardware calibrator for your monitor, but even if you can't, it's always good to have an idea of just how well or poorly your monitor and related systems in your computer are performing.
Here's an easy way to determine if you have some of the more common major problems. Open the attached image in Photoshop using whatever computer, monitor and settings that you usually use.
If you can't clearly distinguish twenty patches in each of the rows, you've got a problem. If the gray patches in the top row don't look perfectly gray to you, or if some look a bit warm and others look a bit cool, you've got a somewhat different problem. FWIW, my system has absolutely no problem distinguishing all patches in all four rows, and the top row is perfectly colorless.
Many desktop computers and monitors designed for conventional office work won't be able to distinguish patch #1 from #2, and #19 from #20 in the top row. Such systems may even have problems distinguishing #2 from#3 and #18 from#19.
If your system is any worse than this, you've got a problem so serious that it will make anyone with a half-way decent monitor (ie, photography and graphics professionals) see something very different from what you expect and want them to see when they look at your images. This may be why you received so many consistent comments in this and some previous threads about your images being too dark.
One final thought. If working properly, a hardware calibrator for your monitor will always improve its performance. However, they can't work miracles. Some monitors (and graphics cards, etc.) are so intrinsically poor that they just can't be improved enough to ever be useful for color-critical work.
HTH,
Tom