Player Movement Style like HL1 Thread

Hello guys and thanks for having the time to read my post.

I'm new here and also new in game modding, I've learned a lot of things here and elsewhere to how to make a mod with source SDK base.

I want now to make a movement, jumping, staring, air accel, speed style in Hl2(SDK 2013) Mod exactly the same way of Half-life 1 (goldsrc)

I've tried a lot of experiences like modifying some .CPP files gamemovement.cpp and others, but I failed with some errors in my visual studio 2013

because I don't have knowledge of how to use it xD, just try to change some same code values.

I also tried to explore some .dlls but i don't have the permission or it's impossible to explore the dlls in bin file ( client.dll server.dll)

can you please help to make this idea or show me what code I need to edit for the character movement.

Thank you in advance