mjhjmtu

I'm trying to represent 3 points in a 3D Cartesian plane. I can do the Cartesian plane but I can not make the grid and color the parts of the plan in yellow, orange and blue. Can you help me?

documentclassstandalone
usepackagetikz
begindocument

begintikzpicture[x=1pt, y=1pt, z=-0.5pt] % Agh
% Let's draw some 3D axes
coordinate (x) at (100,0,0);
coordinate (y) at (0,100,0);
coordinate (z) at (0,0,100);
foreach axis in x,y,z
draw[-latex] (0,0,0) -- (axis);

endtikzpicture

enddocument

This should get you started

documentclassarticle
usepackagetikz
usetikzlibrary3d
usetikzlibrarycalc

begindocument

 begintikzpicture [x=(-0.6cm,-0.4cm), y=(1cm,0cm), z=(0cm,1cm), scale=1]
 beginscope[canvas is zy plane at x=0]
 fill[blue, opacity = 0.2] (0, 0) rectangle (6, 6);
 draw[gray!40] (0, 0) grid (6, 6);
 endscope

 beginscope[canvas is zx plane at y=0]
 fill[orange, opacity = 0.2] (0, 0) rectangle (6, 8);
 draw[gray!40] (0, 0) grid (6, 8);
 draw[black, -latex] (0, 0) -- (6.5, 0) node[left] $z$;

 draw[gray, -latex] (0, 0) -- (-3.5, 0);
 foreach z in 1,...,6 draw (z, -0.1) -- (z, 0.1) node[left]z;
 foreach z in -3,...,-1 draw[gray] (z, -0.1) -- (z, 0.1) node[left]z;

 endscope

 beginscope[canvas is yx plane at z=0]
 fill[yellow, opacity = 0.2] (0, 0) rectangle (6, 8);
 draw[gray!40] (0, 0) grid (6, 8);

 draw[black, -latex] (0, 0) -- (6.5, 0) node[above] $y$;
 draw[black, -latex] (0, 0) -- (0, 8.5) node[above] $x$;

 draw[gray, -latex] (0, 0) -- (0, -8.5);
 foreach x in 0,...,8 draw (-0.1, x) -- (0.1, x) node[right]x;
 foreach x in -8,...,-1 draw[gray] (-0.1, x) -- (0.1, x) node[right]x;

 draw[gray, -latex] (0, 0) -- (-4.5, 0);
 foreach y in 1,...,6 draw (y, -0.1) -- (y, 0.1) node[below]y;
 foreach y in -4,...,-1 draw[gray] (y, -0.1) -- (y, 0.1) node[below]-y;
 endscope

 fill[black] (2, 4, 3) circle (0.05) node[above]$P$;
 draw[red, thick] (0, 4, 0) -- (2, 4, 0);
 draw[blue, thick] (2, 4, 0) -- (2, 4, 3);
 draw[green, thick] (2, 0, 0) -- (2, 4, 0);

 endtikzpicture
enddocument