The easiest thing ...is to make mistakes

No mathematical background is necessary, only handle its mouse.

  here is your draw tool    the pen tool
Let's play with this tool a little to become more familar with it

All you need is this image ( right click > copy > and Paste as a new Image in PSP)

right click on the layer "background" > promote background layer

select all white background with the magic wand    >   Suppr  >select none (Ctrl +D)

images > canvas size > width: 350 , height: 300 , center

increase, and zoom 250%

set the option to :
create on vector
mode
connect segments
show nodes

  click left mouse button on the red pixels of the drawing in A
so click left mouse button and drag it in any directions

that's what you see, a line with two handles


Noticed that a new vectorial layer was added in the layer palette

  release the button , when you see it.
And now left-click at point B and drag in any direction

between A and B a curve appear (color: red , 2 pixels width) You can modify , push in , pull out

  you should be able to draw this

... your mouse in A after B , and again ...

don't forget !   your best friend    "undo"

  you are on B : right click to pull up the edit menu. go to the node type and choose "cusp",

the segment is divided in two parts and the handles can be separated

  and so on , at each node you choose "cusp" (sorry I forgot 'D' )

  important  


always : A to B to C ....and so :
for example you are in C and you want to rotate the handle in A, it is possible but after you have to click on C (with "end") before the next curve CD

  Yes you've done it!
congratulation !    now we have to save this shape ....

  here is the layer palette

  open the layer ";vector 1";

right click on the layer "New Path"
to open the menu "properties"    

you can also find it in   Objects > Properties

  you have this


  change like this

I called the layer New Path : "test"

   the shape can now be exported

   name it : "cloud"

   important   

it is necessary you choose differents names
here : test ≠ cloud

and now I search for my shape  
(like this with PSP 9)
 

The first part is now finished

With this cloud I do a tile


  Open a new raster layer

171*171 , and draw
I used for the outline : blue( #D0E1F1 ), and flood fill is white ( #FFFFFF ).
Select the cloud

draw some clouds
with this tool you can resize and turn .
with this one reveal the node and modify the curves as you wish.



all the clouds are on differents layers, when all the shapes are drawing

   convert the layer   "Vector1"   to raster layer,
add or erase some pixels ,


  shading

I use 3D effects cutout (vertical -1 , horizontal 0 , opacity 75 , blur 7 ) outline color #DOE1F0 and flood fill #FFFFFF.
I added pixels with the airbrush       (color: #DOE1F0)
density (20) opacity (30 / 40)

It is finished!

I hope this small cloud is now in your Preset Shape Tool
if you