help im trying to install some flats and it saying to open with internet explorer then makes me redownload it over and over again im not what wrong im doing
It sounds like the issue you are having is you don't have a default program associated with the file extension you downloaded and so by default it's trying to open in internet explorer.
If it came in a zip folder windows 7+ can open it natively, but if it's a rar or tar.gz you will need to download and install Winzip or Winrar to extra the files.
Otherwise it sounds like you just need to copy the files into the correct folders in order to be able to use them.
Installing Sets: To install a set into your park, you must first download from the link, (CC or Steam). Open the package file in the NoLimits 2 Editor. File > Extract Package > Okay. Navigate to where the package was extracted on Windows' File Exporter. My sets will either begin with RIDE_xxxx or SET_xxxx. COPY (don't MOVE) the RIDE_xxxx / SET_xxxx into your park's directory. NOTE: Some parks will have the set in a .zip folder, use the .zip folder. The .zip folder ensures that every single file of the set is included in it.