I am running Ubuntu 11.10. I was able to compile the hello world fine, but it doesn't run.

I did the sdltest.c section simply copy/pasting your code into my newly made file. and did the same for the "Makefile" for the sdltest, but when I tried to compile the Makefile for the sdltest.c here's what I got:
Running tool: Build

Using Makefile from ~/Desktop/sdltest
make: Entering directory `/home/tina/Desktop/sdltest'
gcc -c sdltest.c
gcc -lSDL sdltest.o -o sdltest
sdltest.o: In function `main':
sdltest.c:(.text+0xa): undefined reference to `SDL_Init'
sdltest.c:(.text+0x23): undefined reference to `SDL_SetVideoMode'
sdltest.c:(.text+0x3c): undefined reference to `SDL_Quit'
sdltest.c:(.text+0x4d): undefined reference to `SDL_PollEvent'
sdltest.c:(.text+0x73): undefined reference to `SDL_MapRGB'
sdltest.c:(.text+0x92): undefined reference to `SDL_FillRect'
sdltest.c:(.text+0xa1): undefined reference to `SDL_Flip'
make: Leaving directory `/home/tina/Desktop/sdltest'
collect2: ld returned 1 exit status
make: *** [compile] Error 1

Exited: 512

any help would be great!

Thanks!