Compile Extension

[Experto]

How do I build an extension?
When I compile is getting to the format plugin (smx)

[Sillium]

An Extension will never compile to an smx.
An Extension will compile to a .dll or .so
http://wiki.alliedmods.net/Writing_Extensions

Plugins will be compiled to .smx
http://wiki.alliedmods.net/Category:SourceMod_Scripting

[Experto]

The information contained there are very few...

Is there any tutorial for beginners?

[berni]

The information contained there are very few...

Is there any tutorial for beginners?

If you want to build extensions you should google for "C++" and "Sourcemod SDK", plenty of results.