Well. Movie maker actually could do this, but probably you did not make the right approach.

one long picture moving left

If you need a long picture you could assemble a long picture, not a series of images.

Then you can use Gimp to assemble them and use Movie Maker with one of the panning movements it has.

But Probably you are looking for a compositing program.

A nice Free alternative is Hit Film Express and of course, you can use Blender too.

That is if you really need a movie.

If you do not, because you need this on a webpage, you probably should use a CSS animation.

Well. Moviemaker actually could do this, but probably you did not make the right approach.

one long picture moving left

If you need a long picture you could assemble a long picture, not a series of images.

Then you can use Gimp to assemble them and use Movie Maker with one of the panning movements it has.

But Probably you are looking for a compositing program.

A nice Free alternative is Hit Film Express and of course, you can use Blender too. Another free alternative is using Davinci Resolve's Dynamic Zoom tool.

That is if you really need a movie.

If you do not, because you need this on a webpage, you probably should use a CSS animation.