sorry but, I dont think we can help you if you really dont understand what we're saying?
A typical downloaded file for OMSI 2 would be in the .zip or .rar or .7z format. You need to open these types of files with a program (either 7-Zip, WinRAR etc). Then, inside the .zip file would usually be folder like OMSI 2, then showing eg. Fonts and Vehicles folders. Then you would extract these folders to your OMSI 2 directory, eg. C:\OMSI 2 or C:\Games\OMSI 2. A video tutorial would be good for you if you don't get it.