Hey i am new to photo editing in general but have watched some tutorials on the basics of Krita already and tried searching for an answer to my question.

I am wondering how i blend images together?

For example if i tried to use the polygonal selection tool to crop something out of a pic. When i tried to attach what i cropped out onto another pic it stood out too much. How do i make stuff blend together better so cropped images don't stand out so much when i place them on another image? For example if i want to replace someones hand, it doesn't blend well.

Sorry if i am not explaining right.

Using another tool would hardly help the original poster... That said, it's a very generic question, and the answer probably is, follow more tutorials on photo editing. Pretty much all applications have the same design and feature set at heart, so what you learn for one, will work for the other.

There is something called feathering in all applications. In Krita it is in select menu > feather selection the shortcut is shift + F6. After you select the part that you want to copy , do a feather selection, the value you input will determine how much smooth the edges will be, the pixels will smoothly merge into transparency depending on the value.

If you would like to do this type of cut-outs often, I would recommend (as mentioned above) to invest some time in learning the basics of photo editing.

My thinking is that your cut-out stand too much from the background because it may have a totally different color brightness, saturation, contrast, etc. Krita has color level controls that can work either on a layer or the whole image, if for example your cut-out image is too rich in colors and the background isn't, even with a good "cut" the image will not "blend", in that case you adjust the colors (and this is a really extensive topic on all the ways it can be achieved) until it matches those in the background, etc.

I think that tinkering with those levels plus the above recommendation on feathered selections may give you a better overall result