At the time of writing, there is no text-balloon feature in DraftSight. Here is a suggested work-around for the missing feature.

Briefly:
Draw a polyline balloon shape.
From that shape create a block.
Insert the block where ever needed.
Place text within the bounds of the balloon body.

In detail:
(for a 30 x 10 mm (1.2 x .4 in) rounded rectangle)

Draw the balloon.
         Use the rectangle tool to draw a 30 x 10 mm (1.2 x .4 in) rectangle.
                   DRAW < RECTANGLE and follow prompts.
         Use the fillet tool to round the corners to radius 3 mm (1/8 in).
                   MODIFY < FILLET and follow prompts.
         Add a narrow, vee-shaped pointer stem near the middle of the lower edge of the rectangle with the open ends of the vee exactly on the edge of the rectangle.
         Use the legs of the vee to trim the rectangle to open the vee at their junction with the rectangle.
                   MODIFY < TRIM and follow prompts.
         Ensure that all entities of the shape are combined into a single polyline.
         Enter EDITPOLYLINE on the command line and follow the prompts to convert (if necessary) the first entity to a polyline and JOIN the remaining entities to it.
         WIDTH for the polyline can also be set if desired.

Create the block.
          Enter MAKEBLOCK on the command line.
          In the Block Definition window work through the options to create the block from the balloon drawing, removing the initial drawing from the drawing space.
          Insert the block in the drawing.
                    Use INSERT < BLOCK... to place a copy of the balloon in the drawing.
                              Insert it un-exploded to use the balloon exactly as it is.
                              Insert it exploded if you want to be able to edit individual copies of the balloon to fine-tune them.
                              (The exploded block my be scaled (bi-directional) stretched (uni-directional) and, for the pointer, grip-edited.)
                             The inserted block may also be exploded after insertion if necessary.

Place required text within the bounds of the balloon body.
          Use either DRAW < TEXT... < NOTE or DRAW < TEXT... < SIMPLE NOTE and follow any prompts.
          Combine the text and balloon into a group so that they can later be handled like a single entity.
                    Enter ENTITYGROUP on the command line and follow the prompts.

Suggestions:

A similar technique may be employed to create blocks for other balloon shapes as they are needed.

If you are going to need this block on other occasions, export it to a drawing and save it in your library of blocks. Consider too, inserting a copy of the block in your template drawing so that it is available each time you use that template.

To allow this block to be inserted at a specific width proceed as follows:
          Start with the balloon drawing as created above.
          Scale it to one drawing unit across.
          Create the block from the one-unit scaled drawing instead of the original drawing.
Now for a balloon ten units wide on insertion insert the block with a scale of ten and so on.

[User of DS (Free) V1R2.1 on Windows 7 Home Premium.]
27 Aug 2012, 15:20 (NZ standard time)