STM32 Simple Timer in Eclipse
You need to add all used HAL .c files to your project. The easiest way:

Download the CubeMx. Create the project for your micro. Configure the clock. You can also configure another peripherals (including the timers) - but you probably want to learn how to configure them - so do not use the Cube for it.

Next generate the project.

Then in the eclipse : File -> Import 


Next -> 



Browse the directory where you have generated the source code



Select the project. Check Copy project into workspace and Finish

And you are done.