Hi,
If your host doesn't support .NET 4, you should download the .NET 3.5 mojoPortal installation package instead of the .NET 4. Once you are using the right .NET version of mojoPortal, installation will probably go smoothly. When you upload the files, be sure to follow the instructions here: http://www.mojoportal.com/uploadingfilestoahostedserver.aspx.
HTH,
Joe D.