Welcome and your English is just fine...

Try to get Gimp and Inkscape as a raster and a vector drawing application.

Dungeonforge is a free stamp / icon based mapping tool which is useful to have
on hand.

For 3D there is sketchup from google which a few people use and also Blender 3D which is a really powerful 3D app, free but real hard to get into if your brave.

Post some maps when you have some