my compiler cant find the iostream.h

its a good idea to install build-essential if you want to code. this package will pull usefull and important stuff (not all needed) but you dont have to search stuff you need which is missing at the moment

sudo apt-get install build-essential

i already installed the build-essential thanks anyway

Seems you need to install the mingw32 package

This has nothing to do with build-essential or mingw32.

You have specified the wrong header. C++ headers, such as iostream do not have a .h extention.

so you want

#include <iostream>

not
#include <iostream.h>

Note that similarly, for C headers used in c++, these have "c" prepended to the name, and no .h suffix

so in c you might write:

#include <math.h>

but in c++ you write:

#include <cmath>

Actually, the original C headers are still supported in C++. It's the C-style C++ headers (such as <iostream.h>) that are not supported anymore (except on a few compilers, such as Microsoft Visual C++). Please note that using these headers is not valid C++ by the current C++ standard, so you should consider avoiding them even when using compilers that do support them for backward compatibility.

There is actually a difference between including <cmath> and <math.h> (and for other C headers, such as cstdlib/stdlib.h, cstdio/stdio.h, and so forth). Symbol names defined in these headers (such as names of functions) are defined in the std namespace in the <cX> versions, but in the global namespace in the <X.h> versions.

See https://answers.launchpad.net/ubuntu/+source/gcc-defaults/+question/143691 and posts #1 and #6 in https://answers.launchpad.net/ubuntu/+source/gcc-defaults/+question/143699 for details.