To save a bitmap so you can load it in Thred,  you can use Window's Paint.  Start by selecting the Windows Start menu.  Paint is under Accessories.  Left click  on the name to launch it.

You open a file in Paint by browsing in the same way you do for Irfanview.  If you need help with that look at Graphics One

Once you have the picture on the Paint screen, select "Save as" to see the screen shown above.  Then select "monochrome bitmap" under "save as type".  A picture saved this way should load into Thred. 

A 24-bit bitmap should also load in Thred.  If you have problems with one, check the file size.   Sometimes Thred seems to crash when you load a bitmap that is very large.  It probably hasn't actually crashed, it is just that large bitmaps are extremely slow to load.   It is a good idea to "resample" a bitmap that is very large.  A file about 100,000 bytes (or 1 K)  in size is reasonably fast.  You can use larger files, but expect the computer to be slower.  Bitmap processing can usually be made faster by getting a faster video card.

Graphics  One

Graphics  Two

Graphics  Three

Graphics  Four

Graphics  Five