Hi, mojoPortal.sln will be located in the root of the folder in which you downloaded the source. From the size you're quoting, I'd say you got a truncated download for some reason. The full mojoPortal source code download should be in the neighborhood of 239 MB. Compiled, it will be north of 600 MB (I can't say exactly, because I have some of my own custom features in my copy).
Jamie