Need help with linux //will pay

So I used @CSEngineer13 's guide on how to set up fabiano's source on a linux VPS
but I get this error when I try to run wServer :

ht tp://imgur. com/yV3 XU78

I've asked a programmer to check it out and he said he thinks it's because some of the code uses .NET 4.6
and they haven't made 4.6 for linux yet ... so he told me I could downgrade the server to the 4.5 .net version and I basically have no clue on how to do that.. if anyone got it to work and would be willing to help me i would be really gratefull + i would pay

Thank you in advance !

Update mono on your linux server.

http://www.mono-projec*****m/docs/get...install/linux/