Lessons 1-3, intro to coding: variables, functions, if/else branches, loops, etc.
Lessons 4-6, trade system coding: trend trading, counter trend trading, trading with frequency filters, series, trade signals, backtesting, optimizing, walk forward analysis, portfolio/basket trading, money management.
The language is lite-C for the Zorro platform. It has the same C language syntax as MQL4, so the first 3 lessons are basically identical to MQL4 coding. Only the trade system coding in C is a little simpler because MQL4 does not support series and other elements. For this reason, C code is shorter and less complex than MQL4. But the basic principles are the same. Have fun!