I am very new to UE4, so I apologise is the answer is obvious. I recently found a site called ‘Stevie’s Corner’ which displayed a ton of really cool, free assets, and their download links alongside for UE4. They downloaded as WinRAR files (which I can’t seem to change) automatically, and when they were done I put them in my documents. I tried and tried to import them to UE4. When I dragged the WinRAR files in, it said that they were in the wrong format as an error message. Even after extracting files, all I have is normal document file of the asset download, and in it are things like audio, textures, materials, blueprints etc as their own folders, but there is nothing I can actually import that will give me the whole asset to use in UE4. I looked it up everywhere, but it seems only I have this problem? Any ideas? Thanks.
Are there any .uasset files in those folders? If so you need to paste the entire folder structure into your project’s content folder and they will be accessible in the content browser of your project…you don’t have to import them into UE4. After looking over his blog most of the assets he is sharing such as the Free Foliage Pack from the forums made by fighter5347 will come with a .uproject file that you can open with UE4. Others such as the Infiltrator Demo will need to be downloaded through the Launcher, that one can be found on the Learn Tab of the launcher.
Edit: Had to repost answer first one failed for some reason.
Thank you very much, this was genuinely very helpful 
When I import the .uasset it never woks. The Textures don’t come and the shape is in little pieces.