Open the image in your Paint program.
Click the 'image' tab on top and click the 'draw opaqua' option on the bottom so that the tick disappears.
Via the "View" tab, make sure the "toolbox" is ticked.
Clicl on the "A" in the left column and then place your pointer on the image where you want to have the text, hold you left mouse button down and pull accross and down, and let the button go where you want it to stop. You will now have a 'typing window' where you can add text to your heart's content.
With a bit of playing around with the edges of the typing window you can place your typed text wherever you like.