well to initialize, you use Opengl-sdl initializations, which is just a little more than standard SDL.
Then you set OPENGL as Orthographic 2d projection. You can disable all 3d stuff such as depth buffer etc.
At this point you can draw sprites drawing opengl quads (2 triangles). You use UV coordinates to choose the sprite in a sprite sheet.
It is possible to build a easy to use blitting function, with usual parameters such as destination rectangle, source, etc.

The only problem is that the texture must be squared with power-of-2 size, a limitation that you probably don't have in SDL.
This can possibly create some problems such arranging the sprite in a squared spritesheet.

But there are *lots* of benefits, first of all performances (standard SDL go really slow on my pc (20-30 fps for empty project), while OPENGL runs hundreds of FPS *with* objects), but you also get:
- performant and easy scaling
- performant and very customizable transparency (shadows, explosions, etc)
- rotations
- lighting & colors (you can choose the base color when you blit, think like drawing a sprite onto a colored piece of paper).

If you like, i can help you out with some code for this things.